Nucleic acid test deployed to screen donor blood supply for Zika in US
A newly developed, highly sensitive nucleic acid test has been deployed for screening of the donor blood supply in Puerto Rico and in the Houston-area, according to a recent MMWR report.
“Summer is heating up, and so is Zika,” Thomas R. Frieden, MD, MPH, director of the CDC, said during a media briefing. “We are sharing information on what may be our most accurate real-time leading indicator of Zika activity in Puerto Rico.”
Thomas R. Frieden
The cobas Zika blood test (NAT, Roche Molecular Systems) is a nucleic acid test which was authorized by the FDA under an investigational new drug application. During the media briefing, Frieden emphasized the test’s highly-sensitive accuracy for detecting Zika pathogens in blood samples. The FDA has recommended donor blood sample screening or donor deferral in areas where Zika virus is currently endemic. On April 3, local screening of the donor blood supply began in Puerto Rico using NAT on individual donor plasma samples.
“The availability of an investigational test to screen donated blood for Zika virus is an important step forward in maintaining the safety of the nation’s blood supply, especially for those U.S. territories already experiencing active transmission,” Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, said in a press release. “In the future, should Zika virus transmission occur in other areas, blood collection establishments will be able to continue to collect blood and use the investigational screening test, minimizing disruption to the blood supply.”
Between April 3 and June 11, a total of 68 Zika-infected blood samples were identified through NAT testing; Frieden stated that these 68 cases represent 0.5% of the donor blood supply tested. However, the rate has been increasing, with the highest rate of 1.1% infected samples identified in the latest week of testing. While these numbers are not meant to be nationally representative, this increase likely reflects an increase in infection incidence within the population of Puerto Rico, according to the report.
“Based on the best information available, Zika infections appear to be increasing rapidly in Puerto Rico,” Frieden said. “The implication of this is, that in the coming months, it is possible that thousands of pregnant women in Puerto Rico could become infected with Zika. This could lead to dozens or hundreds of infants being born with microcephaly in the coming year.”
Frieden noted that while the FDA investigational new drug designation for NAT recommended that the test be used in areas where Zika is currently endemic, U.S.-based testing began at the Gulf Coast Regional Blood Center in Houston, Texas on May 23, 2016. According to Frieden, no Zika-infected blood samples have been identified through this testing. Further, Zika is not endemic in the United States and currently the FDA recommends deferring people who have visited endemic areas from donating blood.
“The Blood Center is trying to be proactive regarding the Zika virus,” Susan Rossmann, MD, PhD, chief medical officer of The Blood Center, said in a press release. “We have agreed to help in development of a new test to do whatever we can to minimize the risk of transmission of the virus via transfusion.”
Frieden stated that the blood supply is safe, and there is currently almost no risk of Zika being transmitted through blood transfusion. According to the report, a single case in Brazil is the only reported case of Zika infection via the bloody supply.
“The blood supply is being tested in Puerto Rico, the blood donors are being screened in the U.S., and any positive blood samples are being removed from the system,” Frieden said during the media briefing. “We don’t think there is a risk to the blood supply. We are working very intensively with our health department, government and community colleagues in Puerto Rico to provide services for pregnant women to reduce their chances of getting infected and to control mosquitoes. This takes a whole community, and although we know we can’t make the risk zero, if we can reduce it some… every infant whose infection doesn’t occur is a tragedy prevented.”—by David Costill
Disclosure: The researchers report no relevant financial disclosures.