FDA Approval of the Pfizer-BioNTech COVID-19 Vaccine: Frequently Asked Questions

September 17, 2021 – September 29, 2021 R46913

FDA Approval of the Pfizer-BioNTech COVID-19 September 29, 2021
Vaccine: Frequently Asked Questions
Kevin J. Hickey
On August 23, 2021, the U.S. Food and Drug Administration (FDA) announced its regulatory
Legislative Attorney
approval of the Pfizer-BioNTech Coronavirus Disease 2019 (COVID-19) vaccine for people 16

years of age or older. The Pfizer-BioNTech vaccine is the first COVID-19 vaccine—and the first
Erin H. Ward
vaccine based on messenger RNA (mRNA) technology—to be licensed by FDA. Previously, the
Legislative Attorney
Pfizer-BioNTech vaccine was available in the United States only under an Emergency Use

Authorization (EUA), a distinct regulatory pathway that allows FDA to authorize use of a drug,
biologic, or medical device prior to approval during a public health emergency.
Agata Bodie
Analyst in Health Policy
Pfizer and BioNTech are marketing their licensed vaccine under the new brand name Comirnaty

(pronounced koe-MIR-na-tee). Comirnaty has the same ingredients and formulation as the Pfizer-
BioNTech vaccine that is authorized under the EUA. The two products differ in branding and

labeling but can be used interchangeably without any impact on safety or effectiveness.
Although Comirnaty is fully approved by FDA for administration to individuals 16 years and older, an EUA remains in effect
for the Pfizer-BioNTech COVID-19 vaccine. Among other things, the reissued EUA authorizes the Pfizer-BioNTech vaccine
for uses that FDA had previously authorized but fall outside the scope of FDA’s approval of Comirnaty. Such uses include
the administration of the vaccine to children aged 12 to 15 and third doses of the vaccine regimen for certain
immunocompromised individuals. The EUA also authorizes use of Comirnaty for those purposes to allow for interchangeable
administration of the two vaccines.
To encourage rapid development and administration of medical countermeasures during a public health emergency, the
Public Readiness and Emergency Preparedness Act (PREP Act) allows the Secretary of Health and Human Services to
provide liability protections to manufacturers, distributors, and administrators of medical countermeasures. The Secretary
invoked the PREP Act with respect to the COVID-19 pandemic in a declaration effective February 4, 2020. Under the current
PREP Act declaration, manufacturers, distributors, and administrators of COVID-19 vaccines (along with other COVID-19
countermeasures) are generally immune from lawsuits based on injuries relating to the use of the vaccines. Liability
immunity under the PREP Act applies to both licensed and authorized COVID-19 vaccines and thus generally applies in the
same manner to both Comirnaty and the Pfizer-BioNTech vaccine. However, the PREP Act may not protect “off label” uses
of the vaccine—that is, uses covered neither by the EUA nor by the biologics license.
Some employers, businesses, and schools require proof of vaccination for certain activities to protect their employees,
customers, and students from COVID-19. Such “vaccine mandates” take different forms and have largely been sustained
when challenged in court. As a practical matter, FDA’s approval of Comirnaty may result in greater use of vaccine mandates
by these entities to the extent that some of them previously did not require vaccination because no COVID-19 vaccine had
been fully licensed by FDA. FDA’s approval may also diminish uncertainty surrounding the legality of such vaccine
mandates, although the legal authority for and limitations on these mandates are largely the same for both licensed and
authorized vaccines.
Congressional Research Service

FDA Approval of the Pfizer-BioNTech COVID-19 Vaccine: Frequently Asked Questions

n August 23, 2021, the U.S. Food and Drug Administration (FDA) approved the
Coronavirus Disease 2019 (COVID-19) vaccine manufactured by Pfizer and BioNTech
O for individuals 16 years of age or older.1 The Pfizer-BioNTech COVID-19 vaccine is the
first COVID-19 vaccine—and the first vaccine based on messenger RNA (mRNA) technology—
to be licensed by FDA.2 Pfizer and BioNTech will market their licensed COVID-19 vaccine under
the brand name Comirnaty (pronounced koe-MIR-na-tee).
Prior to approval, the Pfizer-BioNTech vaccine was available in the United States only under an
Emergency Use Authorization (EUA).3 An EUA is a distinct regulatory pathway from the
ordinary biologics licensure pathway that allows FDA to authorize use of a drug or biologic prior
to approval in circumstances such as a public health emergency.4 FDA first issued an EUA for the
Pfizer-BioNTech vaccine on December 11, 2020, and has reissued the EUA several times since
then, such as to authorize the vaccine in additional groups—for example, children 12 to 15 years
of age.5 A revised EUA remains in effect for the Pfizer-BioNTech vaccine.6
FDA’s approval of Comirnaty has caused some confusion about the scope of FDA’s approval, the
relationship between Comirnaty and the Pfizer-BioNTech COVID-19 vaccine, and other issues.7
This report addresses some common questions about FDA’s approval of Comirnaty.
Frequently Asked Questions
Has the Pfizer-BioNTech COVID-19 vaccine been fully approved by FDA?
Yes. On August 23, 2021, FDA licensed (i.e., approved)8 the first COVID-19 vaccine, Comirnaty,
manufactured by Pfizer-BioNTech. The vaccine is licensed for the prevention of COVID-19,
caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in individuals 16
years of age and older.9

1 FDA, “FDA Approves First COVID-19 Vaccine,” press release, August 23, 2021, https://www.fda.gov/news-
events/press-announcements/fda-approves-first-covid-19-vaccine.
2 FDA, “FDA Approves First COVID-19 Vaccine.”
3 FDA, EUA letter to Pfizer, September 22, 2021, p. 1, https://www.fda.gov/media/150386/download.
4 21 U.S.C. §360bbb-3.
5 FDA, EUA letter to Pfizer, September 22, 2021, pp. 1-2.
6 On the same day FDA approved the Comirnaty BLA, FDA reissued the Pfizer-BioNTech vaccine EUA to incorporate
its approval of Comirnaty. FDA, EUA letter to Pfizer, August 23, 2021, pp. 1-2, https://web.archive.org/web/
20210824120845/https://www.fda.gov/media/150386/download. On September 22, 2021, FDA reissued the EUA again
to authorize third doses of the vaccine for additional categories of individuals determined to be at high risk for severe
COVID, including individuals 65 years of age and older. FDA, EUA letter to Pfizer, September 22, 2021, p. 7.
7 See, for example, Angelo Fichera, “Researcher Distorts Facts on COVID-19 Vaccine Approval, Liability,”
FactCheck.org, August 30, 2021, https://www.factcheck.org/2021/08/scicheck-researcher-distorts-facts-on-covid-19-
vaccine-approval-liability/; Reuters Fact Check, “Fact Check-Media Reports Have Not Lied about Pfizer-BioNTech’s
FDA Approval,” August 27, 2021, https://www.reuters.com/article/factcheck-fda-pfizer/fact-check-media-reports-
have-not-lied-about-pfizer-biontechs-fda-approval-idUSL1N2PY0OL; and Glenn Kessler, “The False Claim That the
Fully-Approved Pfizer Vaccine Lacks Liability Protection,” Washington Post, August 30, 2021,
https://www.washingtonpost.com/politics/2021/08/30/false-claim-that-fully-approved-pfizer-vaccine-lacks-liability-
protection/.
8 Biologics are a subset of drugs and subject to many of the same statutory requirements. However, while small
molecule, chemically synthesized drugs are approved by FDA via a new drug application under the Federal Food,
Drug, and Cosmetic Act, biologics such as vaccines are licensed via a biologics license application under the Public
Health Service Act.
9 FDA, “FDA Approves First COVID-19 Vaccine.” See also FDA, Approval Letter to BioNTech Manufacturing
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FDA Approval of the Pfizer-BioNTech COVID-19 Vaccine: Frequently Asked Questions

To obtain licensure from FDA, BioNTech Manufacturing GmbH, in partnership with Pfizer,
submitted a biologics license application (BLA) to the agency for review. The BLA for Comirnaty
included clinical trial safety and effectiveness data and other information that built on data
previously submitted to FDA in Pfizer-BioNTech’s November 2020 EUA request for the Pfizer-
BioNTech COVID-19 vaccine.10
FDA received the BLA on May 18, 2021.11 The agency granted the BLA priority review,
assigning it a review goal date of January 16, 2022. FDA also had previously designated the
vaccine as a fast track product.12 Fast track designation may be granted to a vaccine that is
intended to prevent a serious disease or condition and for which nonclinical or clinical data
demonstrate the product’s potential to address an unmet medical need.13 The designation confers
certain benefits, such as expedited review and eligibility for rolling review, meaning that FDA
may review portions of the BLA before the completed application is submitted.14 FDA issued its
decision to license Comirnaty in 97 days, or about three months after receiving the complete BLA
from Pfizer-BioNTech.15
What is Comirnaty?
Comirnaty is the proprietary name (i.e., the brand name) under which the FDA-licensed vaccine
that has been known as the Pfizer-BioNTech COVID-19 vaccine (or BNT162b2) will be
marketed.16 The proprietary name is the exclusive name of a drug or vaccine that is owned by a
company under trademark law. Pharmaceutical products are often marketed under a brand name,
which the company selects and FDA approves as part of the BLA review process.17 In the BLA
approval letter, FDA indicated that Pfizer and BioNTech may label and market the licensed
vaccine as Comirnaty,18 which, according to the companies, “represents a combination of the
terms COVID-19, mRNA, community, and immunity.”19

GmbH, Pfizer Inc., August 23, 2021, https://www.fda.gov/media/151710/download. The approval letter states that
FDA is “issuing Department of Health and Human Services U.S. License No. 2229 to BioNTech Manufacturing
GmbH, Mainz, Germany, under the provisions of section 351(a) of the Public Health Service Act controlling the
manufacture and sale of biological products. The license authorizes you to introduce or deliver for introduction into
interstate commerce, those products for which your company has demonstrated compliance with establishment and
product standards.”
10 FDA, Approval Letter to BioNTech Manufacturing GmbH, Pfizer.
11 FDA, Summary Basis for Regulatory Action—Comirnaty, p. 5, https://www.fda.gov/media/151733/download.
12 FDA, Summary Basis for Regulatory Action—Comirnaty, p. 5.
13 21 U.S.C. §356(b). FDA, “Guidance for Industry Expedited Programs for Serious Conditions—Drugs and
Biologics,” May 2014, p. 9, https://www.fda.gov/media/86377/download.
14 21 U.S.C. §356(d). FDA, “Guidance for Industry Expedited Programs for Serious Conditions—Drugs and
Biologics,” p. 10.
15 FDA, “First COVID-19 Vaccine Approval Media Call,” August 23, 2021, at 19:05 minutes.
16 FDA, Summary Basis for Regulatory Action—Comirnaty, p. 3; FDA, “Comirnaty and Pfizer-BioNTech COVID-19
Vaccine,” accessed August 27, 2021, https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-
2019-covid-19/comirnaty-and-pfizer-biontech-covid-19-vaccine; and Pfizer, “Pfizer and BioNTech Receive
Authorization in the European Union for COVID-19 Vaccine,” December 21, 2020, https://www.pfizer.com/news/
press-release/press-release-detail/pfizer-and-biontech-receive-authorization-european-union.
17 FDA, “Contents of a Complete Submission for the Evaluation of Proprietary Names,” Guidance for Industry, April
2016, pp. 5-7, https://www.fda.gov/media/72144/download.
18 FDA, Approval Letter to BioNTech Manufacturing GmbH, Pfizer.
19 Pfizer, “Pfizer and BioNTech Receive Authorization in the European Union for COVID-19 Vaccine,” press release,
December 21, 2020, https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-receive-
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What is the scope of FDA’s biologics license for Comirnaty?
Comirnaty is licensed as a two-dose vaccine for the prevention of COVID-19 in individuals 16
years of age and older. It is not licensed for use in individuals under 16 years of age. It is also not
licensed to be administered as a third dose to individuals who are immunocompromised, or as a
booster dose to individuals determined to be at high risk for severe COVID-19. The EUA for the
Pfizer-BioNTech COVID-19 vaccine, however, does cover these uses, as explained below in the
section “What is the scope of the current EUA for the Pfizer-BioNTech vaccine?”
In determining whether to license a vaccine for a specific use, FDA reviews the data and
information submitted by the manufacturer in the BLA and inspects the facilities in which a
vaccine is made to ensure that the product meets standards for safety, purity, and potency (i.e.,
effectiveness).20 The scope of Comirnaty’s licensure is based on the supporting data and
information FDA received in Pfizer-BioNTech’s BLA. This support included data regarding the
safety and effectiveness of two doses of the vaccine administered in individuals 16 years of age
and older, building on the data and information previously submitted by the companies in their
initial EUA request.
For example, the Pfizer-BioNTech COVID-19 vaccine EUA was granted based on safety and
effectiveness data derived from an ongoing, randomized, controlled, and blinded trial of
approximately 36,000 individuals 16 years of age and older who did not have evidence of SARS-
CoV-2 infection within a week of receiving the second dose of the vaccine. About half of this
group received the vaccine (n=18,198) and the other half placebo (n=18,325).21 The vaccine was
found to be 95% effective at preventing symptomatic COVID-19, with eight cases of COVID-19
identified in the vaccine group and 162 in the placebo group.22
FDA evaluated follow-up data from this trial as part of the Comirnaty BLA, with the updated
analysis including approximately 19,993 individuals in the vaccine group and 20,118 in the
placebo group.23 The updated analysis found an effectiveness rate of 91%, based on the
occurrence of 77 cases of COVID-19 in the vaccine group and 833 COVID-19 cases in the
placebo group.24 In determining whether to license the vaccine, FDA evaluated these data, along
with information about the manufacturing facilities, longer term follow-up safety data from the
trial, adverse events reported from use of the vaccine under EUA, and other information.
Under the terms of licensure, Comirnaty may be manufactured only in facilities identified and
approved under the vaccine’s BLA.25 Comirnaty’s labeling must be identical to that approved by
FDA and must include warnings and precautions, contraindications, dosage and administration
instructions, and storage and handling conditions, among other information.26 The Comirnaty

authorization-european-union.
20 42 U.S.C. §262(a)(1)(C).
21 FDA, “Q&A for Comirnaty (COVID-19 Vaccine mRNA),” accessed August 30, 2021, https://www.fda.gov/
vaccines-blood-biologics/qa-comirnaty-covid-19-vaccine-mrna. See also FDA, EUA letter to Pfizer, December 11,
2020, p. 23, https://www.fda.gov/media/144416/download.
22 FDA, EUA letter to Pfizer, December 11, 2020, p. 23.
23 FDA, “Q&A for Comirnaty (COVID-19 Vaccine mRNA);” and FDA, Summary Basis for Regulatory Action—
Comirnaty, p. 19.
24 FDA, “Q&A for Comirnaty (COVID-19 Vaccine mRNA);” and FDA, Summary Basis for Regulatory Action—
Comirnaty, p. 19.
25 FDA, Approval Letter to BioNTech Manufacturing GmbH, Pfizer.
26 FDA, Approval Letter to BioNTech Manufacturing GmbH, Pfizer. A vaccine manufacturer must submit proposed
vaccine labeling as part of a BLA. See 21 C.F.R. §601.14. Labeling requirements for drugs and biologics are specified
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approval letter also requires that any manufacturing changes that deviate from those approved
under the BLA be submitted to FDA, specifies requirements for advertising and promotional
labeling, and outlines postmarketing study obligations for the manufacturer.27
As required for all licensed vaccines, Pfizer and BioNTech must report adverse events associated
with Comirnaty to FDA.28 Each serious and unexpected adverse experience must be reported as
soon as possible but no later than 15 days from initial receipt of the information by the
manufacturer.29 Periodic safety reports are required for each adverse experience not reported in a
15-day alert report and must be submitted to FDA at quarterly intervals for the first three years
following approval and at annual intervals thereafter.30
Is there any difference between Comirnaty and the Pfizer-BioNTech vaccine?
The BLA-licensed vaccine Comirnaty is the same formulation as the EUA-authorized Pfizer-
BioNTech COVID-19 vaccine. Specifically, both Comirnaty and the Pfizer-BioNTech vaccine
contain “a nucleoside-modified messenger RNA (mRNA) encoding the viral spike glycoprotein
(S) of SARSCoV-2” formulated in the same lipids (i.e., organic compounds that are insoluble in
water such as fats).31 Because the vaccines contain the same formulation, doses distributed under
the EUA can be used interchangeably with doses licensed under the BLA without safety or
effectiveness concerns.32 The distinction between Comirnaty and the Pfizer-BioNTech COVID-19
vaccine is legal rather than scientific, as further discussed in the section “Why did FDA refer to
Comirnaty and the Pfizer-BioNTech vaccine as “legally distinct”?”
If Comirnaty is now licensed, why did FDA reissue an EUA for the
Pfizer-BioNTech vaccine?
There are several reasons FDA reissued the Pfizer-BioNTech vaccine EUA when it licensed the
Comirnaty vaccine under the BLA. In the August 23, 2021 letter, FDA stated that it reissued the
EUA “to clarify that the EUA will remain in place for the Pfizer-BioNTech COVID-19 vaccine
for the previously-authorized indication and uses, and to authorize use of COMIRNATY
(COVID-19 Vaccine, mRNA) under this EUA for certain uses that are not included in the
approved BLA.”33 Reissuing the EUA has several legal and practical effects.
First, the EUA allows the Pfizer-BioNTech vaccine and Comirnaty to be used for patient
populations and clinical situations that are not included in the Comirnaty BLA.34 FDA approved
Comirnaty to be marketed only for a two-dose regimen for individuals 16 years of age and
older.35 The EUA authorizes both the Pfizer-BioNTech vaccine and Comirnaty to be used for a
two-dose regimen for individuals 12 to 15 years of age, for certain immunocompromised

in 21 C.F.R. §§201.56, 201.57, for example.
27 FDA, Approval Letter to BioNTech Manufacturing GmbH, Pfizer.
28 FDA, Approval Letter to BioNTech Manufacturing GmbH, Pfizer.
29 21 C.F.R §600.80(c).
30 21 C.F.R §600.80(c).
31 FDA, Summary Basis for Regulatory Action—Comirnaty, p. 3; and FDA, EUA letter to Pfizer, December 11, 2020,
p. 11.
32 FDA, EUA letter to Pfizer, September 22, 2021, p. 3.
33 FDA, EUA letter to Pfizer, August 23, 2021, p. 2. See also FDA, EUA letter to Pfizer, September 22, 2021, p. 2, n. 9.
34 FDA, EUA letter to Pfizer, September 22, 2021, p. 2.
35 FDA, Approval Letter to BioNTech Manufacturing GmbH, Pfizer.
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individuals to receive a third dose of the vaccine, and for single booster doses at least six months
after the primary vaccination series for certain individuals determined to be at high risk for severe
COVID.36 Without the EUA, individuals 12 to 15 years of age would not be authorized or
approved to receive a Pfizer-manufactured COVID-19 vaccine, nor could any individuals receive
a third dose or booster. (For a summary of the populations covered by the EUA and the approved
BLA, see Table 1.)
Second, reissuing the EUA allows vaccine administrators to use the remaining doses of the
Pfizer-BioNTech vaccine that have not yet been administered. FDA notes in the EUA that there
“remains a significant amount of Pfizer-BioNTech COVID-19 vaccine that was manufactured and
labeled in accordance with” the EUA.37 The Pfizer-BioNTech vaccine has the same formulation
as Comirnaty but is legally distinct and can be manufactured, marketed, distributed, and
administered only pursuant to the EUA.38 (For more information on what it means for the two
vaccines to be legally distinct, see “Why did FDA refer to Comirnaty and the Pfizer-BioNTech
vaccine as “legally distinct”?”) If FDA had revoked the EUA when it approved the Comirnaty
BLA, the remaining Pfizer-BioNTech vaccine doses would have been unauthorized and unable to
be used.
Third, the EUA facilitates the logistics of distributing and administering Pfizer-manufactured
COVID-19 vaccines. The EUA authorizes use of Comirnaty for the patient populations and
clinical situations for which the Pfizer-BioNTech vaccine is authorized but that are not covered
by the BLA: a two-dose regimen for individuals 12 to 15 years of age, a third dose for certain
immunocompromised individuals 12 years and older, and a booster dose for certain individuals
18 years and older determined to be at high risk of severe COVID.39 By authorizing Comirnaty
for these uses, and clarifying that Comirnaty is interchangeable with the Pfizer-BioNTech
vaccine, the EUA allows vaccine administrators to use whichever vaccine is available—whether
it is labeled Comirnaty or Pfizer-BioNTech—which may avoid potential shortages or other
logistical complications.40

36 FDA, EUA letter to Pfizer, September 22, 2021, p. 7.
37 FDA, EUA letter to Pfizer, September 22, 2021, p. 13.
38 FDA, EUA letter to Pfizer, September 22, 2021, p. 3, n. 10; 42 U.S.C. §360bbb-3.
39 FDA, EUA letter to Pfizer, September 22, 2021, p. 7.
40 FDA, EUA letter to Pfizer, September 22, 2021, pp. 2 and 7.
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Table 1. Comparison of Patient Populations Covered by the Pfizer-BioNTech EUA
and Comirnaty BLA
Pfizer-BioNTech EUA
Comirnaty BLA
Patient Population
Pfizer-BioNTech
Comirnaty

Individuals 0 to 11
x
x
x
Individuals 12 to 15
√
√
x
Individuals 16 and older
√
x
√
Third dose for certain
√
√
x
immunocompromised individuals
Single booster dose at least six
√
√
x
months after completing the primary
vaccination series for certain
individuals determined to be at high
risk for severe COVID-19
Source: CRS.
Notes: EUA = Emergency Use Authorization; BLA = biologics license application. On August 12, 2021, FDA
authorized third doses for individuals 12 years of age and older who have undergone solid organ transplants or
been diagnosed with similarly immunocompromising conditions. On September 22, 2021, FDA reissued the EUA
to authorize a single booster dose at least six months after completing the primary vaccination series for
(1) individuals 65 years of age or older, (2) individuals 18 to 64 years of age who are at high risk of severe
COVID-19, and (3) individuals 18 to 64 years of age whose institutions or occupations involve frequent exposure
to SARS-CoV-2 such that they are at high risk of serious complications of COVID-19.
What is the scope of the current EUA for the Pfizer-BioNTech vaccine?
The Pfizer-BioNTech vaccine EUA, as reissued on September 22, 2021, authorizes a two-dose
regimen of the Pfizer-BioNTech vaccine for individuals 12 years or age and older, a third dose of
the Pfizer-BioNTech vaccine for individuals 12 years of age and older who have undergone solid
organ transplants or been diagnosed with similarly immunocompromising conditions, and single
booster doses at least six months after completing the primary vaccination series for certain
categories of individuals determined to be at high risk for severe COVID. Specifically, the EUA
authorizes booster doses for (1) individuals 65 years of age or older, (2) individuals 18 to 64 years
of age who are at high risk of severe COVID-19, and (3) individuals 18 to 64 years of age whose
institutions or occupations involve frequent exposure to SARS-CoV-2 such that they are at high
risk of serious complications of COVID including severe COVID-19.41 The EUA also authorizes
a two-dose regimen of Comirnaty for individuals 12 to 15 years of age, a third dose of Comirnaty
for individuals 12 years or age and older who have undergone solid organ transplants or have
been diagnosed with similarly immunocompromising conditions, and a single booster dose six
months after the primary vaccination series for the same categories authorized for the Pfizer-

41 FDA, EUA letter to Pfizer, September 22, 2021, p. 7. The September 22, 2021, EUA revises the existing EUA,
which FDA originally issued for the Pfizer-BioNTech vaccine on December 11, 2020, for a two-dose regimen in
individuals 16 years of age or older. FDA, EUA letter to Pfizer, December 11, 2020. Since the initial EUA, FDA has
amended the EUA several times and issued three additional decision memoranda. The first, issued May 10, 2021,
authorized the Pfizer-BioNTech vaccine to be used in individuals 12 to 15 years of age. FDA, EUA letter to Pfizer,
May 10, 2021, https://www.fda.gov/media/148542/download. The second, issued August 12, 2021, authorized a third
dose of the Pfizer-BioNTech vaccine to be administered to individuals who have undergone solid organ transplants or
have been diagnosed with similarly immunocompromising conditions. FDA, EUA letter to Pfizer, August 12, 2021,
https://www.fda.gov/media/151613/download.
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BioNTech vaccine.42 These uses are not included in the approved Comirnaty BLA (see “What is
the scope of FDA’s biologics license for Comirnaty?”).
The scope of the Pfizer-BioNTech vaccine EUA is based on the supporting data and information
submitted to FDA by the companies in their EUA requests. As FDA has received additional data
to support that the vaccine may be effective in preventing COVID-19 in certain pediatric
populations (i.e., 12 to 15 year olds) and under expanded dosing regimens (i.e., a third dose for
certain immunocompromised individuals and single booster doses for individuals determined to
be at high risk for severe COVID-19), the agency has amended and reissued the original Pfizer-
BioNTech vaccine EUA to include these indications.
FDA initially granted the Pfizer-BioNTech vaccine EUA on December 11, 2020, based on safety
and effectiveness data in individuals 16 years of age and older.43 FDA subsequently reissued the
EUA on May 10, 2021, to authorize the use of the vaccine in individuals 12 to 15 years of age
based on clinical trial safety and effectiveness data in more than 2,000 individuals in this age
group.44 FDA again amended the Pfizer-BioNTech vaccine EUA on August 12, 2021, as requested
by Pfizer, to allow for the use of a third dose of the vaccine in certain immunocompromised
individuals based on safety and effectiveness data in the published literature.45
On August 23, 2021, FDA reissued the EUA after it approved the Comirnaty BLA “to clarify that
the EUA will remain in place for the Pfizer-BioNTech COVID-19 vaccine for the previously-
authorized indication and uses, and to authorize use of COMIRNATY (COVID-19 Vaccine,
mRNA) under this EUA for certain uses that are not included in the approved BLA.”46 FDA
reissued the EUA again on September 22, 2021, to authorize single booster doses at least six
months after the primary vaccination series for certain categories of individuals determined to be
at high risk for severe COVID-19.47
Under the terms of the EUA, the Pfizer-BioNTech vaccine may be manufactured only in a facility
identified and agreed upon in Pfizer’s EUA request.48 The Pfizer-BioNTech vaccine vial label and
carton labels must be clearly marked for “Emergency Use Authorization.”49 Pfizer must distribute
the Pfizer-BioNTech vaccine to emergency response stakeholders directly or through authorized
distributors as directed by the U.S. government, such as the Centers for Disease Control and
Prevention (CDC).50 The Pfizer-BioNTech vaccine must be administered by vaccine providers, as

42 FDA, EUA letter to Pfizer, September 22, 2021, p. 7.
43 FDA, EUA letter to Pfizer, December 11, 2020.
44 FDA, EUA letter to Pfizer, May 10, 2021.
45 FDA, EUA letter to Pfizer, August 12, 2021.
46 FDA, EUA letter to Pfizer, August 23, 2021, p. 2.
47 FDA, EUA letter to Pfizer, September 22, 2021, p. 7.
48 FDA, EUA letter to Pfizer, September 22, 2021, p. 8.
49 FDA, EUA letter to Pfizer, September 22, 2021, p. 8.
50 FDA, EUA letter to Pfizer, September 22, 2021, pp. 6-7. Pfizer and the U.S. government determine which entities are
“authorized distributor(s).” FDA, EUA letter to Pfizer, September 22, 2021, p. 6, n.14. The letter defines emergency
response stakeholder as public health agencies and their delegates. FDA, EUA letter to Pfizer, September 22, 2021, p.
6, n. 15.
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defined by the EUA.51 Fact sheets must be made available to vaccination providers and
recipients.52
The EUA imposes reporting requirements on Pfizer in connection with adverse events.53 It also
imposes conditions on emergency response stakeholders and vaccination providers to distribute
and administer the Pfizer-BioNTech vaccine in accordance with the EUA’s terms and to provide
relevant information to stakeholders and recipients.54 The EUA further provides conditions
related to advertising, promoting, and exporting the Pfizer-BioNTech vaccine.55 Finally, the EUA
requires that Comirnaty vaccines be manufactured, distributed, and administered in accordance
with the EUA terms when administered for uses authorized by the EUA (i.e., for individuals 12 to
15 years of age, third doses for certain immunocompromised individuals, and single booster
doses for certain individuals determined to be at high risk for severe COVID-19), except that
Comirnaty vaccines manufactured and labeled in accordance with the BLA are deemed to meet
the EUA’s manufacturing, labeling, and distribution requirements.56
Unlike the BLA, which will remain in effect indefinitely unless it is withdrawn for safety or
efficacy reasons, the EUA remains in effect only until the Secretary revokes the declaration that
an emergency exists due to the COVID-19 pandemic that justifies the emergency use of
unapproved drugs and biological products.57
Why did the FDA Vaccines and Related Biological Products Advisory
Committee recommend booster doses only for certain categories of
individuals?
The Vaccines and Related Biological Products Advisory Committee (VRBPAC) made its
recommendation as to booster doses of the Pfizer-BioNTech vaccine based on the data available
from clinical trials and real-world case studies, as well as on statutory standards for approving or
authorizing biologics such as vaccines.
On September 17, 2021, FDA convened a meeting of the VRBPAC to discuss the supplemental
BLA submitted by Pfizer-BioNTech for approval of a single booster dose of Comirnaty for
individuals 16 years of age and older.58 Pfizer and BioNTech initiated submission of their

51 FDA, EUA letter to Pfizer, September 22, 2021, p. 7. As defined in the EUA, for vaccines administered in the United
States, a vaccination provider is “a facility, organization, or healthcare provider licensed or otherwise authorized by the
emergency response stakeholder … to administer or provide vaccination services” and “who is enrolled in the CDC
COVID-19 Vaccination Program.” FDA, EUA letter to Pfizer, September 22, 2021, p. 7, n. 16.
52 Specifically, vaccination providers must be provided with a fact sheet titled “Fact Sheet for Healthcare Providers
Administering Vaccine (Vaccine Providers): Emergency Use Authorization (EUA) of Pfizer-BioNTech COVID-19
Vaccine to Prevent Coronavirus Disease 2019 (COVID-19).” Vaccine recipients must be provided with a fact sheet
titled “Vaccine Information Fact Sheet for Recipients and Caregivers About COMIRNATY (COVID-19 Vaccine,
mRNA) and Pfizer-BioNTech COVID-19 Vaccine to Prevent Coronavirus Disease (COVID-19).” FDA, EUA letter to
Pfizer, September 22, 2021, p. 8.
53 FDA, EUA letter to Pfizer, September 22, 2021, p. 10.
54 FDA, EUA letter to Pfizer, September 22, 2021, pp. 11-12.
55 FDA, EUA letter to Pfizer, September 22, 2021, pp. 13.
56 FDA, EUA letter to Pfizer, September 22, 2021, p. 13-14.
57 FDA, EUA letter to Pfizer, September 22, 2021, p. 14; 42 U.S.C. §300bbb-3.
58 FDA, “Vaccines and Related Biological Products Advisory Committee September 17, 2021 Meeting
Announcement,” accessed on September 27, 2021, https://www.fda.gov/advisory-committees/advisory-committee-
calendar/vaccines-and-related-biological-products-advisory-committee-september-17-2021-meeting-
announcement#event-materials.
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supplemental BLA to FDA on August 25, 2021.59 After consideration of the available data, as
well as the statutory standards for approving or authorizing biologics such as vaccines, VRBPAC
voted not to recommend approval of a single booster for individuals 16 years of age and older.
VRBPAC instead voted to recommend an EUA for single booster doses for individuals 65 years
of age and older and for individuals 18 to 64 years of age at high risk for severe COVID-19 or
with frequent exposure to SARS-CoV-2 in their institution or occupation that put them at high
risk of serious complications from COVID-19, including severe COVID-19.60 FDA reissued the
Pfizer-BioNTech vaccine EUA on September 22, 2021, with new authorizations consistent with
VRBPAC’s recommendations.61
During the September 17, 2021 hearing, FDA and Pfizer-BioNTech presented the data available
on changes in immunity over time after full vaccination and side effects associated with
administering booster doses.62 The Committee also heard presentations on data from the United
Kingdom regarding real-world effectiveness of COVID-19 vaccines and on data from Israel
regarding the protection provided by booster doses against infection and severe cases of COVID-
19.63 The hearing also included a presentation on the epidemiology of the pandemic and
comments from members of the public.64
The standards for approving a biologic under a BLA are different from those for authorizing a
medical countermeasure, such as a vaccine, for emergency use under an EUA. To approve a BLA
(or supplemental BLA) under the Public Health Service (PHS) Act, FDA must determine that the
sponsor has demonstrated the product (e.g., a vaccine) is safe and effective.65 EUAs are subject to
a different standard for authorization. To issue an EUA, FDA must determine, among other
things, that the known and potential benefits of using the countermeasure to diagnose, treat, or
prevent the relevant disease or condition outweigh the known and potential risks of such use.66
Thus, to issue an EUA for a booster dose of the Pfizer-BioNTech vaccine, FDA would have to
determine that the known and potential benefits of administering a single booster dose to

59 Pfizer and BioNTech, “Pfizer and BioNTech Initiate Rolling Submission of Supplemental Biologics License
Application to U.S. FDA for Booster Dose of Comirnaty in Individuals 16 and Older,” press release, August 25, 2021,
https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-initiate-rolling-submission.
60 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 7:51-7:52 minutes,
https://www.youtube.com/watch?v=WFph7-6t34M.
61 FDA, EUA letter to Pfizer, September 22, 2021, p. 3.
62 FDA, “Comirnaty (COVID-19 Vaccine, mRNA) Supplemental Biologics License Application for a Booster Dose in
Individuals 16 Years of Age and Older,” presentation, September 17, 2021, p. 6, https://www.fda.gov/media/152242/
download (hereinafter VRBPAC Meeting Agenda); FDA, “Application for Licensure of a Booster Dose of
COMIRNATY, COVID-19 Vaccine, mRNA,” presentation, September 17, 2021, https://www.fda.gov/media/152238/
download; FDA, “FDA Review of Effectiveness and Safety of COMIRNATY (COVID-19 Vaccine, mRNA) Booster
Dose Biologics License Application Supplement,” presentation, September 17, 2021, https://www.fda.gov/media/
152239/download; Pfizer and BioNTech, “BNT162b2 [COMIRNATY (COVID-19 Vaccine, mRNA)] Booster (Third)
Dose,” presentation, September 17, 2021, https://www.fda.gov/media/152240/download.
63 VRBPAC Meeting Agenda, p. 5; Jonathan Sterne, University of Bristol, “Real-World Effectiveness of COVID-19
Vaccines,” presentation, September 17, 2021, https://www.fda.gov/media/152241/download; Israel MOH, Weizmann
Institute of Science, Gertner Institute, Hebrew University, and Technion, “Booster Protection Against Confirmed
Infections and Severe Disease – Data from Israel,” presentation, September 17, 2021, https://www.fda.gov/media/
152205/download.
64 VRBPAC Meeting Agenda, p. 5; Sara Oliver, CDC, “Updates to COVID-19 Epidemiology and COVID-19
Vaccines,” presentation, September 17, 2021, https://www.fda.gov/media/152243/download.
65 42 U.S.C. §262(a); 21 U.S.C. §355.
66 21 U.S.C. §360bbb-3(c)(2)(B).
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individuals 18 years of age and older outweigh the known and potential risks of administering the
booster dose.
During the Committee discussion, VRBPAC members raised concerns about the available data’s
adequacy, particularly with respect to the risks and benefits for younger individuals not at high
risk for severe COVID-19. Committee members expressed concerns that the value for younger
individuals with lower risks of COVID-19 complications was not as clear, and that such
individuals might be at higher risk for adverse events from additional doses.67 In particular,
multiple Committee members raised concerns about whether the risk of myocarditis
(inflammation of the heart muscle)—particularly for men under the age of 40—might be
increased with a third dose.68 Others observed that myocarditis is a short-term condition, versus
the potential longer-term consequences of COVID-19, and that the infrequency of myocarditis as
a side effect may mean that sufficient data are obtainable only through widespread use of boosters
rather than clinical trials.69 The Committee noted that the pathogenesis of myocarditis is poorly
understood, and more data are needed before moving forward with a booster dose in the general
population.70 In addition, Committee members observed that Pfizer’s clinical trial was small, so it
provided limited data on risks associated with boosters, particularly in younger age groups.71
Given that unauthorized booster doses have been administered to healthy individuals, some
Committee members were surprised about the lack of strong safety evidence presented, and
indicated that FDA’s failure to request such data was a missed opportunity.72 A related challenge
noted by members was that additional data and studies were forthcoming, but not yet available to
inform the Committee’s deliberations.73 Finally, some members questioned whether there were
adequate data about whether and how much the immune response decreased over time after the
primary vaccination series, primarily due to reliance on measuring antibody levels rather than
assessing cell-mediated immunity.74
Due to the limitations of the Pfizer clinical trial data presented, the Committee also considered
Israeli data.75 Committee members observed that because Israel had administered booster doses
beginning with older populations, limited data were available about the risks and benefits for
younger populations.76 Committee members also questioned whether the Israeli data were
representative of the expected risks and benefits for the U.S. population, which has a lower
vaccination rate. In particular, in the United States, transmission is driven primarily by
unvaccinated individuals, and thus providing a third dose to the already vaccinated may provide
only a marginal benefit for reducing overall disease burden.77 Members observed that those who

67 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:18-6:19.
68 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:24-6:30, 6:39-40.
69 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:45-6:46, 6:53-
6:54.
70 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:25.
71 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:14-6:15, 6:45,
6:56.
72 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:14-6:15.
73 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:38.
74 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:17-6:18, 6:35.
75 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:14-6:15, 7:05.
76 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:30-6:32, 7:05.
77 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:17-6:18, 6:30-
6:32, 6:35, 6:37.
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stand to benefit most from additional doses that reduce the disease’s severity are those at highest
risk of severe complications from COVID-19.78 This approach may be reevaluated as more data
become available.79
Following the presentations and public comments provided at the hearing, VRBPAC voted on
whether the safety and effectiveness data from the Pfizer-BioNTech clinical trial (C4591001)
supported the approval of a Comirnaty booster dose administered at least six months after
completing the primary vaccination series for use in individuals 16 years of age and older.80 Two
Committee members voted to approve the supplemental BLA and sixteen voted not to approve
it.81 Following a discussion of the first voting question, FDA recognized that Committee members
had several concerns related to the benefit-risk balance of a booster in the population of
individuals 16 years and older, as well as concerns about the data and level of evidence available
to support the safety and effectiveness of a booster dose.82 Given this, FDA formulated a new
question involving an EUA. The second voting question asked whether, based on the totality of
scientific evidence available, including from clinical trial C4591001, the known and potential
benefits outweighed the known and potential risks of providing a Pfizer-BioNTech vaccine
booster at least six months after the primary vaccination series to individuals 65 years of age and
older and individuals at high risk of severe COVID-19.83 The Committee unanimously voted yes,
recommending issuance of an EUA of a booster dose for those populations.84
VRBPAC’s recommendation to authorize booster doses only for certain populations was based on
the data available and presented on September 17, 2021. The Committee could vote in a future
meeting to modify its recommendations regarding such doses based on additional data on
declining immunity, the effectiveness of booster doses after various intervals following the
primary vaccination series, or the side effects of booster doses. Similarly, VRBPAC could vote to
recommend approving booster doses for the population covered by the September 22, 2021 EUA
or some other population, pursuant to a resubmitted supplemental BLA. While FDA takes
VRBPAC’s recommendation into consideration, it is not binding on the agency. As such, FDA
may choose to expand the EUA or approve the vaccine for additional uses even if VRBPAC does
not recommend such uses.
Can COVID-19 vaccine providers use the Comirnaty-labeled vaccine
interchangeably with the Pfizer-BioNTech vaccine?
Yes. The revised EUA states that Comirnaty can be used interchangeably with the Pfizer-
BioNTech vaccine because it is the same formulation.85 This means vaccine administrators may
use Comirnaty for the first dose and Pfizer-BioNTech vaccine for the second dose, or vice versa,
“without presenting any safety or effectiveness concerns.”86 Similarly, either the Comirnaty or

78 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:30-6:32.
79 Ibid.
80 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 6:57.
81 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 7:00-7:02.
82 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 7:42-7:43.
83 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 7:50.
84 FDA, “Vaccines and Related Biological Products Advisory Committee,” September 17, 2021, at 7:51-7:52.
85 FDA, EUA letter to Pfizer, September 22, 2021, p. 3.
86 FDA, EUA letter to Pfizer, September 22, 2021, p. 3, n. 10. In the context of biological products, the standard for
interchangeability is that (1) the biological product is biosimilar to the reference (i.e., brand-name) product; (2) the
biological product can be expected to produce the same clinical result in any given patient as the reference product; and
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FDA Approval of the Pfizer-BioNTech COVID-19 Vaccine: Frequently Asked Questions

Pfizer-BioNTech vaccine may be used for any third doses regardless of which vaccine was used
for the original two-dose regimen.
Why did FDA refer to Comirnaty and the Pfizer-BioNTech vaccine as
“legally distinct”?
In the EUA, FDA states that the Comirnaty and Pfizer-BioNTech vaccines “are legally distinct
with certain differences that do not impact safety or effectiveness.”87 While the Comirnaty and
Pfizer-BioNTech vaccines have the same formulation, they are legally allowed to be marketed
and used pursuant to different legal authorities.88 Specifically, Comirnaty is licensed pursuant to a
BLA issued under the PHS Act (42 U.S.C. §262).89 The Pfizer-BioNTech vaccine is authorized
for emergency use pursuant to the Federal Food, Drug, and Cosmetic (FD&C) Act (21 U.S.C.
§360bbb-3).90
Each product must be manufactured, labeled, marketed, distributed, and administered in
accordance with the requirements of the legal regime under which it was approved or authorized.
These requirements may differ in a number of ways. For example, under the EUA, the Pfizer-
BioNTech vaccine must be accompanied by fact sheets for the vaccine administrator and recipient
informing them, among other things, of the product’s emergency authorization, known and
anticipated risks and benefits, and the right to decline the vaccine.91 Comirnaty need not be
accompanied by this information if it is being administered pursuant to the BLA rather than the
EUA; instead, the PHS Act and other FDA regulatory labeling requirements apply.92
As another example, the Pfizer-BioNTech vaccine may be manufactured only at facilities
identified and agreed upon in Pfizer’s EUA request, must be distributed directly by Pfizer or
through authorized distributors to emergency response stakeholders (as defined in the EUA) as
directed by the U.S. government, and must be administered by vaccination providers (as defined
in the EUA) only to individuals 12 years of age and older in accordance with the uses authorized
by the EUA.93 These limitations do not apply to Comirnaty vaccines manufactured and
distributed pursuant to the BLA; instead, the PHS Act and FD&C Act requirements apply.
Comirnaty may be manufactured only at facilities identified and approved in the BLA.94

(3) if administered more than once to an individual (as the Pfizer-BioNTech and Comirnaty vaccines are due to the
two-dose regimen), the risk of safety and diminished efficacy from switching between the biosimilar and reference
product is not greater than when using the reference product alone. 42 U.S.C. §262(k)(4). FDA appears to have used
the same standard to determine that the Comirnaty and Pfizer-BioNTech vaccines are interchangeable.
87 FDA, EUA letter to Pfizer, September 22, 2021, p. 3, n. 10.
88 FDA, EUA letter to Pfizer, September 22, 2021, p. 3.
89 FDA, Approval Letter to BioNTech Manufacturing GmbH, Pfizer, August 23, 2021; 42 U.S.C. §262.
90 FDA, EUA letter to Pfizer, September 22, 2021.
91 FDA, EUA letter to Pfizer, September 22, 2021, p. 8; FDA, “Fact Sheet for Healthcare Providers Administering
Vaccine (Vaccination Providers): Emergency Use Authorization (EUA) of Pfizer-BioNTech COVID-19 Vaccine to
Prevent Coronavirus Disease 2019 (COVID-2019),” September 22, 2021, https://www.fda.gov/media/144413/
download; FDA, “Vaccine Information Fact Sheet for Recipients and Caregivers About Comirnaty (COVID-19
Vaccine, mRNA) and Pfizer BioNTech COVID-19 Vaccine to Prevent Coronavirus Disease (COVID-19),” September
22, 2021, https://www.fda.gov/media/144414/download.
92 FDA, EUA letter to Pfizer, September 22, 2021, p. 14.
93 FDA, EUA letter to Pfizer, September 22, 2021, pp. 6-7.
94 FDA, Approval Letter to BioNTech Manufacturing GmbH, Pfizer, August 23, 2021.
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FDA Approval of the Pfizer-BioNTech COVID-19 Vaccine: Frequently Asked Questions

What liability protections apply to COVID-19 vaccines?
Under the Public Readiness and Emergency Preparedness Act (PREP Act), the Secretary of
Health and Human Services (HHS) has the authority to limit legal liability for losses relating to
the administration of medical countermeasures—such as diagnostics, treatments, and vaccines—
during a public health emergency.95 In a declaration effective February 4, 2020, the Secretary
invoked the PREP Act and declared COVID-19 to be a public health emergency warranting
liability protections for manufacturers, distributors, and administrators of covered
countermeasures (along with other covered persons).96 If covered by the terms of such a
declaration, the PREP Act generally immunizes a covered person from legal liability for all
claims for loss relating to the administration or use of a covered countermeasure.97
Under the current PREP Act declaration for COVID-19, covered countermeasures include “any
drug, any biologic … or any vaccine manufactured, used, designed, [or] developed … [t]o
diagnose, mitigate, prevent, treat, or cure COVID-19.”98 Covered persons include manufacturers,
distributors, and qualified persons authorized to administer covered countermeasures by federal,
state, tribal, and local public health agencies.99
Thus, vaccine manufacturers, distributors, and authorized health care providers administering the
Pfizer-BioNTech COVID-19 vaccine or Comirnaty are generally immune from legal claims for
injury or other losses resulting from the administration of the vaccine.100 For example, an
individual who suffers an adverse allergic reaction to a COVID-19 vaccine—such as the rare
reported cases of anaphylaxis101—generally cannot sue the vaccine manufacturer for damages
resulting from the injury. Instead, while the declared public health emergency remains in effect,
monetary compensation for any deaths or serious injuries caused by COVID-19 vaccines may be
available from the federal government through the Countermeasures Injury Compensation
Program.102

95 42 U.S.C. §§247d-6d, 247d-6e. For more detail on the scope of liability protections for COVID-19 countermeasures
under the PREP Act, see generally CRS Legal Sidebar LSB10443, The PREP Act and COVID-19: Limiting Liability
for Medical Countermeasures, by Kevin J. Hickey.
96 HHS, “Declaration Under the Public Readiness and Emergency Preparedness Act for Medical Countermeasures
Against COVID-19,” 85 Federal Register 15198, March 10, 2020. The PREP Act declaration has been subsequently
amended nine times to expand the scope of its liability protection in various ways. See HHS, “Public Readiness and
Emergency Preparedness Act,” accessed September 8, 2021,
https://www.phe.gov/Preparedness/legal/prepact/Pages/default.aspx (linking to the PREP Act declaration amendments).
97 42 U.S.C. §247d-6d(a)(1).
98 HHS, “Fourth Amendment to the Declaration Under the Public Readiness and Emergency Preparedness Act for
Medical Countermeasures Against COVID-19 and Republication of the Declaration,” 85 Federal Register 79190,
79196, December 3, 2020. (Subsequent amendments have not altered this section of the declaration.)
99 HHS, “Ninth Amendment to Declaration Under the Public Readiness and Emergency Preparedness Act for Medical
Countermeasures Against COVID-19,” 86 Federal Register 51160, 51163, September 14, 2021.
100 42 U.S.C. §247d-6d(a)(1); see generally CRS Report R46399, Legal Issues in COVID-19 Vaccine Development and
Deployment, by Kevin J. Hickey, Wen W. Shen, and Erin H. Ward, at pp. 32-36. The “sole exception to the immunity”
is a claim for willful misconduct. See 42 U.S.C. §247d-6d(d)(1). “Willful misconduct” as defined in the PREP Act
requires that the covered person acted (i) intentionally to achieve a wrongful purpose; (ii) knowingly without legal or
factual justification; and (iii) in disregard of a known or obvious risk that is so great as to make it highly probable that
the harm will outweigh the benefit. 42 U.S.C. §247d-6d(c)(1)(A).
101 CDC and FDA, “Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Pfizer-BioNTech
COVID-19 Vaccine—United States, December 14-23,” Morbidity and Mortality Weekly Report, vol. 70, no. 2 (January
15, 2021), pp. 46-51, https://www.cdc.gov/mmwr/volumes/70/wr/mm7002e1.htm.
102 Health Resources and Services Administration, “Countermeasures Injury Compensation Program,” accessed
September 8, 2021, https://www.hrsa.gov/cicp; see generally CRS Legal Sidebar LSB10584, Compensation Programs
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Does FDA’s licensure of Comirnaty affect liability protections for COVID-19
vaccines under the PREP Act?
Generally speaking, it does not. Under the PREP Act, “covered countermeasures” include both
(1) “qualified pandemic or epidemic products” and (2) biological products authorized for
emergency use under an EUA.103
Comirnaty is a biological product licensed by FDA to prevent COVID-19 (see “What is the scope
of FDA’s biologics license for Comirnaty?”). It meets the definition of qualified pandemic or
epidemic product and is thus a covered countermeasure under the PREP Act while the PREP Act
declaration remains in effect. For its part, the Pfizer-BioNTech vaccine is authorized under an
EUA to prevent COVID-19 (see “What is the scope of the current EUA for the Pfizer-BioNTech
vaccine?”). It, too, meets the definition of covered countermeasure under the PREP Act.
Because Comirnaty and the Pfizer-BioNTech COVID-19 vaccine are both covered
countermeasures, the liability protections under the PREP Act apply to both products. That is,
assuming that all the other elements for immunity under the PREP Act are met,104 whether the
vaccine’s use is licensed by FDA or authorized under an EUA does not affect the PREP Act’s
liability protections.
Do the PREP Act’s liability protections extend to off-label uses of Comirnaty?
It is not clear whether off-label uses of otherwise covered countermeasures, such as Comirnaty,
would receive the same liability protections under the PREP Act as authorized and approved uses.
Off-label use generally refers to the practice of prescribing or administering a drug or biologic
(such as a vaccine) for a use other than the one or more specific uses FDA approved.105 Such off-
label uses are generally considered to be within the scope of the practice of medicine, with the
physician exercising professional judgment about treatment, and therefore not in violation of the
FD&C Act’s marketing restrictions.106
Following the licensure of Comirnaty, there were reports of parents expressing interest in
vaccinating their younger children who are not covered by the scope of the licensed vaccine or
the EUA-authorized vaccine (i.e., children under 12 years of age) through off-label use of
Comirnaty.107 The CDC has noted that such uses of Comirnaty are not authorized and indicated
that off-label uses therefore “may not be covered” under the PREP Act.108

for Potential COVID-19 Vaccine Injuries, by Kevin J. Hickey and Erin H. Ward.
103 42 U.S.C. §247d-6d(i)(1)(A), (C). A “qualified pandemic product” is defined to include a “biological product that is
… manufactured, used, designed, [or] developed … to diagnose, mitigate, prevent, treat, or cure a pandemic or
epidemic” and that is approved or licensed by FDA. 42 U.SC. §247d-6d(i)(7)(A)-(B).
104 See CRS Legal Sidebar LSB10443, The PREP Act and COVID-19: Limiting Liability for Medical
Countermeasures, by Kevin J. Hickey, for a discussion of those other elements (such as the claim being against a
“covered person” and a causal relationship between the loss and the use of the covered countermeasure).
105 FDA, “Understanding Unapproved Use of Approved Drugs ‘Off Label,’” accessed September 1, 2021,
https://www.fda.gov/patients/learn-about-expanded-access-and-other-treatment-options/understanding-unapproved-
use-approved-drugs-label.
106 See, for example, Buckman Co. v. Plaintiffs’ Legal Comm., 531 U.S. 341, 350 (2001).
107 See, for example, Theresa Gaffney, “‘Tired of Worrying’: As Some Parents Press for Vaccines Off-Label,
Pediatricians Call for Patience,” STAT News, August 27, 2021, https://www.statnews.com/2021/08/27/covid19-
vaccine-off-label-kids/.
108 CDC, “COVID-19 Vaccine FAQs for Healthcare Professionals” (see section “Off-Label Use”), accessed August 30,
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The CDC’s statement reflects legal uncertainty as to whether PREP Act immunity extends to
claims for injuries resulting from off-label uses of a covered countermeasure. For immunity under
the PREP Act to apply, the activity at issue must relate to the administration or use of a covered
countermeasure for which the Secretary of HHS has issued a PREP Act declaration.109 If
providers knowingly administer vaccines to populations currently outside of the EUA or the
approved biologics license for Comirnaty, they would arguably fall outside of the current PREP
Act declaration and therefore not be immunized from liability. In particular, the declaration
contains language excluding uses that exceed the scope of authorization by the relevant public
health authority. For example, the declaration states that “liability protections are afforded to
Covered Persons only for” covered countermeasures that (1) “are related to activities authorized
in accordance with the public health and medical response of the Authority Having Jurisdiction”
or (2) are administered “pursuant to the FDA licensure, approval, clearance, or authorization.”110
The “Authority Having Jurisdiction” refers to the state, federal, tribal, or local “public agency …
that has legal responsibility and authority for responding to an incident.”111 Thus, if providers
intentionally engage in activities that the relevant public health authorities—here, the CDC and
FDA—did not authorize, they may not be immune from claims of legal liability under the PREP
Act declaration for those actions.
Off-label use generally refers to a situation where the provider exercises professional judgment to
prescribe or administer a drug or biologic for an unapproved use. A potentially distinct scenario
may occur when an otherwise-authorized health care provider unknowingly administers the
vaccine to a recipient outside of the currently authorized population. For example, anecdotal
media reports indicate instances of parents misrepresenting the ages of their children to obtain
COVID-19 vaccines.112 In that situation, the health care provider administering the vaccine may
have no reason to know that the vaccine administration was unauthorized under the EUA and
current CDC guidance.
Language in the PREP Act declaration arguably allows health care providers to retain legal
immunity in this situation. The current PREP Act declaration purports to provide immunity even
if the vaccine recipient is outside the covered population if the “qualified person reasonably could
have believed the recipient was in this population.”113 The PREP Act declaration would therefore
arguably reach authorized health care providers who unwittingly administer COVID-19 vaccines
to populations beyond those currently authorized. As the former general counsel of HHS
explained in an advisory opinion (later explicitly incorporated into the operative PREP Act
declaration114), PREP Act immunity should apply to persons who “reasonably could have

2021, https://www.cdc.gov/vaccines/covid-19/hcp/faq.html#off-label-use.
109 42 U.S.C. §247d-6d(a)(1), (b)(1).
110 HHS, “Fourth Amendment to the Declaration Under the Public Readiness and Emergency Preparedness Act for
Medical Countermeasures Against COVID-19 and Republication of the Declaration,” at 79196-97. There are other
covered activities and distribution channels in the PREP Act declaration—such as activities relating to federal
contracts—but these do not appear relevant to the off-label use scenario.
111 HHS, “Fourth Amendment to the Declaration Under the Public Readiness and Emergency Preparedness Act for
Medical Countermeasures Against COVID-19 and Republication of the Declaration,” at 79197.
112 See, for example, Brett Kast, “Some Michigan Parents Reportedly Lying About Their Child’s Age to Get Them
COVID Vaccine,” WXYZ, August 18, 2021, https://www.wxyz.com/news/coronavirus/covid-19-vaccine/some-
michigan-parents-reportedly-lying-about-their-childs-age-to-get-them-covid-vaccine.
113 HHS, “Fourth Amendment to the Declaration Under the Public Readiness and Emergency Preparedness Act for
Medical Countermeasures Against COVID-19 and Republication of the Declaration,” at 79197.
114 HHS, “Fourth Amendment to the Declaration Under the Public Readiness and Emergency Preparedness Act for
Medical Countermeasures Against COVID-19 and Republication of the Declaration” at 79195, n. 19.
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FDA Approval of the Pfizer-BioNTech COVID-19 Vaccine: Frequently Asked Questions

believed” they were covered persons administering a covered countermeasure, even if that belief
later proved mistaken.115 Given the limited case law on the PREP Act, however, it is difficult to
determine whether a court would agree with these constructions of the PREP Act declaration and
statute.116
Separately from the PREP Act issue, the CDC has stated that knowing off-label uses “would be in
violation of the CDC COVID-19 Vaccination Program provider agreement and therefore may not
be reimbursable, and may impact the ability of a provider to remain in the CDC Program, in
addition to other potential sanctions.”117 Thus, whether or not PREP Act immunity applies,
providers engaging in intentional off-label use may be in violation of their contractual
obligations.
VRBPAC, the FDA’s vaccine advisory committee, may ultimately recommend authorizing
additional uses for the Pfizer-BioNTech and other COVID-19 vaccines—such as administration
of the vaccine to children aged 5 to 11 or booster shots for the general adult population that is not
determined to be at high risk for severe COVID-19. FDA would then likely reissue the currently
operative EUA to authorize these additional uses. At that point, such uses would no longer be off-
label but within the scope of an EUA and covered by the PREP Act.
Does FDA’s licensure of Comirnaty affect the authority of employers or
schools to “mandate” COVID-19 vaccines?
As explained in more detail in other CRS products, federal law does not generally preclude
private employers from requiring that their employees be vaccinated but may require these
entities to provide appropriate exemptions based on medical disabilities or religious beliefs.118 As
to government employers and public schools, modern courts have relied on Jacobson v.
Massachusetts—a 1905 Supreme Court ruling holding that the Constitution does not preclude
state governments from mandating vaccination119—to uphold such vaccine mandates (with

115 HHS, “Advisory Opinion on the Public Readiness and Emergency Preparedness Act and the March 10, 2020
Declaration under the Act,” May 19, 2020, p. 2, https://www.hhs.gov/sites/default/files/prep-act-advisory-opinion-hhs-
ogc.pdf. HHS’s interpretation draws on the statutory provision that provides immunity under “circumstances in which
… the covered person reasonably could have believed that the countermeasure was administered or used in accordance
with” population or geographical limitations in the PREP Act Declaration. 42 U.S.C. §247d-6d(a)(4)(B).
116 For example, assuming the PREP Act declaration is read to cover this situation, the liability protections must still
accord with the statute. To be a covered countermeasure under the PREP Act, the vaccine must be approved, licensed,
or authorized for emergency use by FDA. 42 U.S.C. §247d-6d(i)(1)(C), (7)(B). Comirnaty and the Pfizer-BioNTech
vaccine are licensed and authorized for emergency use by FDA, respectively, and are thus covered countermeasures.
Read literally, the PREP Act’s definition of covered countermeasure requires only that “the biological product … is
authorized” (or licensed) and does not speak to the authorization of particular uses. 42 U.S.C. §247d-6d(i)(1)(C),
(7)(B)(i). That said, a court might understand the word authorized (or licensed) to imply that the actual use at issue
must be within the scope of the EUA (or approved biologics license) in order to be a “covered countermeasure.”
117 CDC, “COVID-19 Vaccine FAQs for Healthcare Professionals” (see section “Off-Label Use”).
118 See CRS Legal Sidebar LSB10573, COVID-19 Vaccination Requirements: Potential Constraints on Employer
Mandates Under Federal Law, by April J. Anderson and Victoria L. Killion; see also Equal Employment Opportunity
Commission, “What You Should Know About COVID-19 and the ADA, the Rehabilitation Act, and Other EEO
Laws,” accessed September 9, 2021, https://www.eeoc.gov/wysk/what-you-should-know-about-covid-19-and-ada-
rehabilitation-act-and-other-eeo-laws (“The federal [employment laws] do not prevent an employer from requiring all
employees physically entering the workplace to be vaccinated for COVID-19, subject to the reasonable accommodation
provisions of Title VII [relating to religious objections] and the ADA [relating to disabilities].”).
119 Jacobson v. Massachusetts, 197 U.S. 11, 26–31 (1905); Zucht v. King, 260 U.S. 174, 176 (1922) (“[Jacobson]
settled that it is within the police power of a State to provide for compulsory vaccination.”).
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appropriate exemptions).120 Based on this precedent, legal challenges to public schools’ and
employers’ COVID-19 vaccine mandates have largely been rejected by courts in early stages of
litigation.121
Prior to FDA approval of the Pfizer-BioNTech COVID-19 vaccine, some commentators argued
that the mandates for EUA-authorized vaccines may not be legal under the EUA statute.122 In
particular, Section 564(e)(1)(A)(ii)(III) of the FD&C Act requires the Secretary of HHS to ensure
that individuals receiving EUA products “are informed … of the option to accept or refuse
administration of the product, of the consequences, if any, of refusing administration of the
product, and of the alternatives to the product that are available and of their benefits and risks.”123
In these commentators’ view, this language might suggest that mandating EUA products is
“categorically prohibited” because the recipient must have the “option to accept or refuse
administration of the product.”124 Others read this provision not to prohibit schools’ or employers’
vaccine requirements but merely to require that vaccine recipients receive appropriate
information—such as the FDA fact sheets for COVID-19 vaccines.125
In a recent opinion, the Office of Legal Counsel (OLC)—the division of the Department of
Justice that provides legal advice to the President—considered and rejected the argument that
Section 564(e)(1)(A)(ii)(III) prohibits vaccine mandates.126 In OLC’s view, this section “concerns
only the provision of information to potential vaccine recipients and does not prohibit public or
private entities from imposing vaccination requirements.”127 Consistent with this view, at least
two district courts have rejected this statutory argument.128

120 See CRS Report R46745, State and Federal Authority to Mandate COVID-19 Vaccination, by Wen W. Shen, pp. 3-
4 (collecting cases). Presuming that it acts pursuant to valid statutory and constitutional authority, Jacobson implies
that the federal government has power to require vaccination in some circumstances—for example, for federal
employees. See Executive Order on Requiring Coronavirus Disease 2019 Vaccination for Federal Employees,
September 9, 2021, https://www.whitehouse.gov/briefing-room/presidential-actions/2021/09/09/executive-order-on-
requiring-coronavirus-disease-2019-vaccination-for-federal-employees/; see generally CRS Legal Sidebar LSB10633,
Federal Employees and COVID-19 Vaccination Attestations: Immediate Takeaways, by April J. Anderson, Wen W.
Shen, and Jon O. Shimabukuro.
121 See, for example, Klaassen v. Trustees of Indiana Univ., No. 1:21-CV-238 DRL, 2021 WL 3073926 (N.D. Ind. July
18, 2021) (denying preliminary injunction against Indiana University’s COVID-19 vaccine mandate for students),
motion for injunction pending appeal denied, 7 F.4th 592, 593 (7th Cir. 2021) (“Given [Jacobson], there can’t be a
constitutional problem with [requiring] vaccination against SARS-CoV-2.”); Bridges v. Houston Methodist Hosp., No.
CV H-21-1774, 2021 WL 2399994, at *1 (S.D. Tex. June 12, 2021) (dismissing wrongful termination claim based on
private-employer COVID-19 vaccine mandate); Harris v. Univ. of Massachusetts, No. 21-CV-11244-DJC, 2021 WL
3848012, at *1 (D. Mass. Aug. 27, 2021) (denying preliminary injunction against University of Massachusetts’
COVID-19 vaccine mandate for students); Norris v. Stanley, No. 1:21-CV-756, 2021 WL 3891615, at *1 (W.D. Mich.
Aug. 31, 2021) (denying temporary restraining order against COVID-19 vaccine mandate for Michigan State
University employees); Valdez v. Grisham, No. 21-cv-783, 2021 WL 4145746, at *13 (D.N.M. September 13, 2021)
(denying temporary restraining order and preliminary injunction against COVID-19 vaccine mandate for school
workers, certain health care workers, the governor’s office, and state fair attendees).
122 Efthimios Parasidis and Aaron S. Kesselheim, “Assessing the Legality of Mandates for Vaccines Authorized Via an
Emergency Use Authorization,” https://www.healthaffairs.org/do/10.1377/hblog20210212.410237/full/.
123 21 U.S.C. §360bbb-3(e)(1)(A)(ii)(III).
124 Parasidis and Kesselheim, footnote 122.
125 Anderson, Shen, and Shimabukuro, footnote 120, at 6 (explaining this argument).
126 OLC, “Whether Section 564 of the Food, Drug, and Cosmetic Act Prohibits Entities from Requiring the Use of a
Vaccine Subject to an Emergency Use Authorization,” July 6, 2021, https://www.justice.gov/olc/file/1415446/
download (hereinafter OLC Section 564 Opinion).
127 OLC Section 564 Opinion, p. 7.
128 Bridges v. Houston Methodist Hosp., No. CV H-21-1774, 2021 WL 2399994, at p. *2 (S.D. Tex. June 12, 2021);
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It is therefore not clear that the EUA status of a vaccine has any bearing on the authority of
schools and employers to mandate that vaccine. Now that FDA has approved Comirnaty, legal
arguments against vaccine mandates that relied on COVID-19 vaccines’ EUA status are now
largely moot.129 To that extent, FDA’s approval of Comirnaty may reduce any legal uncertainty
surrounding vaccine mandates.
For the most part, however, the legal authority for COVID-19 vaccine mandates—and the
statutory or constitutional constraints on them—are the same before and after Comirnaty’s
licensure.130 As a practical matter, to the extent that some employers and schools previously
refrained from vaccination mandates because no COVID-19 vaccine had been fully approved by
FDA, the approval of Comirnaty may result in greater use of vaccine mandates.131

Author Information

Kevin J. Hickey
Agata Bodie
Legislative Attorney
Analyst in Health Policy

Erin H. Ward

Legislative Attorney

Valdez v. Grisham, No. 21-cv-783, 2021 WL 4145746, at *5 (D.N.M. September 13, 2021).
129 At the time of this writing, Comirnaty is the only FDA-approved COVID-19 vaccine. The Moderna and Johnson &
Johnson COVID-19 vaccines are available only under an EUA. However, the argument against vaccine mandates based
on the EUA statute would appear to be precluded as long as the vaccine mandate at issue accepts an available FDA-
approved option (here, Comirnaty). See Norris v. Stanley, No. 1:21-CV-756, 2021 WL 3891615, at p. *2 (W.D. Mich.
Aug. 31, 2021) (“[S]hould Plaintiff be offered the FDA-approved Pfizer Comirnaty vaccine, her argument under the
EUA statute would be moot.…”). The legal issue may remain open with respect to vaccine mandates imposed on
individuals 12 to 15 years old, however, as no vaccine is approved for use in this age group. See “If Comirnaty is now
licensed, why did FDA reissue an EUA for the Pfizer-BioNTech vaccine?”
130 There are some exceptions, such as where particular statutory authorities (or, in the employment context, contractual
requirements such as collective bargaining agreements) distinguish between authorized and approved vaccines. For
example, the Department of Defense interprets Title 10, Section 1107a, of the U.S. Code to preclude a mandate for
EUA vaccines unless the President issues a waiver. See OLC Section 564 Opinion, pp. 16-17.
131 See, for example, Deepa Shivaram, “Why Pfizer’s FDA Approval Matters and What It Means for Vaccine
Mandates,” NPR, August 24, 2021, https://www.npr.org/sections/coronavirus-live-
updates/2021/08/24/1030267314/pfizer-vaccine-covid-fda-approval-kids-faq-mandate (“It’s likely we’ll see more
vaccine requirements put in place now that there is one vaccine with full FDA approval.”).
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Disclaimer
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under the direction of Congress. Information in a CRS Report should not be relied upon for purposes other
than public understanding of information that has been provided by CRS to Members of Congress in
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Congressional Research Service
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