< Back to Current Version

Zika Testing Poses Challenges for Blood Centers

Changes from August 12, 2016 to September 2, 2016

This page shows textual changes in the document between the two versions indicated in the dates above. Textual matter removed in the later version is indicated with red strikethrough and textual matter added in the later version is indicated with blue.


CRS INSIGHT Zika Poses New Challenges for Blood Centers August 12, 2016 (IN10544) | Related Authors C. Stephen Redhead Sarah A. Lister | C. Stephen Redhead, Specialist in Health Policy (credhead@crs.loc.gov, 7-2261) Sarah A. Lister, Specialist in Public Health and Epidemiology (slister@crs.loc.gov, 7-7320) Introduction On July 27, the Food and Drug Administration (FDA) advised blood centers in Miami-Dade and Broward counties in Florida to stop collecting blood until they could test each donated unit for Zika virus (ZIKV) using an investigational test that FDA cleared for use earlier this year. OneBlood, which collects blood throughout most of the state, had already decided, after consulting with the Florida Department of Health (FDOH), to suspend collections in south Florida. Two days later, FDOH announced the first cases of local (i.e., mosquito-borne) ZIKV transmission in the continental United States, originating in Miami-Dade county, and OneBlood began testing all blood units collected throughout its service area. These are

Introduction

On August 26, the Food and Drug Administration (FDA) issued an updated guidance recommending that all U.S. blood centers begin testing donations for Zika virus (ZIKV) using an investigational test cleared by FDA. While the recommendation is nonbinding, all blood centers are expected to comply.

Blood donations in Puerto Rico and Florida, the only areas within the United States where local mosquito-borne ZIKV transmission has been confirmed, are already being tested. Testing is also being conducted on donations in high-risk areas of Texas.

The guidance is
the latest in a series of steps to prevent the spread of ZIKV in the blood supply. In February, FDA released a set of donor screening and deferral recommendations,, which U.S. blood banks implemented. FDA also advised The agency also recommended suspending blood collections in areas where ZIKV was being spreadfound to be spreading locally by mosquitoes until testing could be implemented. The Zika-related donor deferrals have exacerbated an already tight U.S. blood supply this summer. Last monthIn July, the nation's blood bankers issued a joint appeal for blood donors to sustain inventories across the country. Figure 1. Blood centers also face the challenge of recovering the costs of ZIKV testing.

Figure 1.
An American Red Cross Worker PreparesTesting Donated Blood for Testing Blood Source: U.S. Department of Defense, 2006.

Evolution of the Zika Threat

ZIKV is transmitted by infected mosquitoes or sexual contact, from mother to fetus, and through contaminated blood transfusion. Prenatal ZIKV infection
U.S. Department of Defense, 2006. Evolution of the Zika Threat The Zika virus, first recognized in Uganda in 1947, is thought to have emerged in the Western Hemisphere early in 2015. Although most cases of ZIKV infection are mild, prenatal infection can cause severe birth defects, including microcephaly. ZIKV is transmitted among humans by the bite of an infected mosquito, by sexual contact, from mother to fetus, and through contaminated blood transfusion. ZIKV has spread from South America into Central America and the Caribbean. Puerto Rico ZIKV is thought to have arrived in the Western Hemisphere early in 2015. Until recently, most U.S. cases of ZIKV infection were among travelers returning from areas with local transmission of ZIKV (i.e., areas where Aedes mosquitoes are spreading the virus). Puerto Rico has experienced local transmission of ZIKV since November 2015 and has been hard hit, with about 14,000 locally acquired infections reported to date. Two counties in Florida have also had local transmission.

While CDC does not anticipate widespread local transmission of ZIKV on the U.S. mainland, it has not ruled out additional "hot spots" of local transmission emerging in the coming weeks.

For the purpose of blood safety, CDC and FDA define areas of active transmission of ZIKV as "having two or more locally acquired cases of Zika virus infection within 45 days." Active transmission can occur in areas with both Aedes mosquitoes and large numbers of travel-associated ZIKV cases. Of potential concern are U.S. states in the South, and along the East and West Coasts.

Response of FDA and the Blood Banks

, with more than 5,600 confirmed infections to date. On July 29, FDOH reported four cases of mosquito-borne transmission of ZIKV originating from one neighborhood in Miami, the first such cases in the continental United States. An additional 18 cases from the same neighborhood were identified over the next few days. Not all of these people had symptoms of illness. The Centers for Disease Control and Prevention (CDC) has issued public health guidance to stem further spread in this area, included an unprecedented recommendation that pregnant women avoid travel to the affected neighborhood. Local officials have expanded mosquito control efforts, and some have called for the travel advisory to be lifted. Response of FDA and the Blood Banks On February 16, 2016, FDA issued donor education, screening, and deferral recommendationsrecommendations for immediate implementation to reduce the risk of transmitting ZIKV by blood transfusion. The agency had concluded that transfusion-transmitted ZIKV was likely, based on possible cases in Brazil and other evidence. Transmission of ZIKV by transfusion was subsequently confirmed. through the blood supply. FDA provided two sets of recommendations. One was for U.S.It advised blood centers in areas without active transmission, which without local transmission, which at the time included the entire continental United States. For those centers, FDA advised deferring—, to defer for four weeks potential donors who (1) reported traveling to an area with active ZIKV transmission (e.g., Puerto Rico, Mexico), (2) engaged in behaviors (including sexual contact) that may have exposed them to ZIKV, or (3) reported symptoms suggestive of ZIKV infection. In areas with localactive transmission, which at the time included only Puerto Rico, FDA was more prescriptive. It recommended suspending blood collections until a ZIKV test was available and, in the meantime, procuring blood products from areas without local transmission. In early March, the Department of Health and Human Services announced that it would coordinate and pay for shipments of blood products to Puerto Rico from blood centers in the continental United States. active transmission. As a result, blood collections in Puerto Rico were halted, and shipments of blood products were flown in from the U.S. mainland. On March 30, FDA announced the availability of a test for ZIKV in donated blood under an Investigational New Drug (IND) application, the first of two such tests. Blood centers in Puerto Rico quickly resumed collections and began sending samples to a testing facility in Florida that had implemented the investigational ZIKV test. OneBlood is one of several blood banks that have recently implemented ZIKV testing under the IND protocol. To date, it is the only one testing blood collected in an area of the U.S. mainland where local mosquito-borne ZIKV transmission has been confirmed. The other blood banks have implemented ZIKV testing as a precaution. FDA will use data from the IND protocols to evaluate the tests for licensure. Blood centers in Florida began testing their donors in late July when the first local ZIKV cases were identified in Miami. (The IND test used for donated blood is different from ZIKV tests used to diagnose illness in patients. Currently, there are no FDA-approved ZIKV diagnostic tests, but FDA has granted emergency use authorizations—EUAs— [EUAs] for several tests under development.) CDC does not anticipate widespread mosquito-borne transmission of ZIKV on the U.S. mainland. However, the affected Miami-Dade neighborhood may be the first of a number of "hot spots" of local ZIKV transmission this summer and fall. In that case, more widespread testing may be needed to adequately protect the blood supply. Blood centers often struggle to maintain adequate inventories during the summer because donors are on vacation and colleges are out of session. The ZIKV donor deferral is just one of several factors making the summer of 2016 even more challenging for blood centers than usual. In May, blood centers raised the minimum hemoglobin level required for males to donate, one of a series of changes in a recent FDA rule that updated and revised existing blood banking regulations. An initial survey of blood banks indicated that this has caused a 2.4% loss of male donors. In June, FDA announced the recall of multiple lots of blood products with unacceptably high white blood cell counts due to a faulty filtering device. White blood cells typically are filtered out to reduce the risk of an adverse reaction caused by the transfusion recipient's own immune response to the foreign cells. under development.)

The updated guidance recommends that the following states implement testing by September 23: Alabama, Arizona, California, Georgia, Hawaii, Louisiana, Mississippi, New Mexico, New York, South Carolina, and Texas. These states were chosen because of their proximity to areas with cases of local mosquito-borne ZIKV or because of other epidemiological factors, such as the number of travel-related cases. All other states and territories should implement testing by November 18.

Blood centers struggle to maintain adequate inventories during the summer when donors are on vacation and colleges are out of session. ZIKV donor deferral is just one of several factors that have made the summer of 2016 more challenging for blood centers than usual.

The guidance should help increase donations in the coming weeks because it allows blood centers that institute testing to discontinue verbal donor screening and deferral for ZIKV risk factors, such as travel history. FDA argues that screening donors in areas with local ZIKV transmission based on their medical history is of limited value given that about 80% of infected individuals show no symptoms.

While all blood centers intend to comply with the guidance, some question whether universal ZIKV testing goes beyond what is necessary to protect the blood supply. For state and local public health officials, testing of blood donors acts as a surveillance system for identifying ZIKV infection in otherwise healthy individuals.

Implementing ZIKV testing is a complex and costly process, though cost recovery is permitted under the IND protocol. In Florida, blood centers reportedly have been able to recover ZIKV testing costs from the hospitals they sell blood products to. Whether blood centers in other parts of the country will be able to recover their testing costs is unclear.