The Food and Drug Administration has revised its guidelines for Zika-testing of donated blood: Instead of only testing donations in areas where active local transmission is a reality, the agency now advises that all blood donations, everywhere, be screened for the virus.
The new recommendation comes weeks after one blood donation, in Miami, was found to be contaminated with the virus. That contamination was detected before the donation was passed to a recipient. "We were able to keep it from the blood supply," says Peter Marks, M.D., director of the FDA's Center for Biologics Evaluation and Research. "So far, there have not been any cases of Zika transmission through blood transfusions."
About one million units of blood are donated by volunteers each month in the U.S. and its territories. In Puerto Rico, about one percent of donations have tested positive for Zika, but in the mainland U.S., only the one Miami donation has been found contaminated.
The "universal testing" edict is already being used in Florida and Puerto Rico, where active Zika transmission is a reality. The FDA has set a goal of implementing the same protocol in 11 additional states within the next four weeks. Those states—Alabama, Arizona, California, Georgia, Hawaii, Louisiana, Mississippi, New Mexico, New York, South Carolina, Texas—are either near an active transmission zone or have a high volume of travel-related cases.
The agency's goal is to implement universal testing in the remaining states within 12 weeks.
More than 50 countries are currently experiencing local Zika outbreaks. More than 8,000 travel-associated cases and more than 2,000 non-travel-related cases, have been reported in the U.S. and its territories. "There is just tremendous uncertainty [about how long the Zika epidemic will last]," Marks says. "We all hope this will be gone, but we have to be prepared for it to go on for awhile."
What You Need to Know
How long does Zika stay in your blood? Zika can persist in human blood for up to 30 days.
So, when is it safe to donate? As long as the virus is not present in your blood, you should be cleared to donate. Zika can persist for much longer in semen (several months) and vaginal secretions (several weeks), but it can't be passed through the blood from those reservoirs.
How will a blood donation center test my blood? The tests being used to detect Zika in blood are nucleic-acid tests. They work by searching for the virus's genetic material in donated blood. These tests are done after the donation, before the blood is made available for recipients. While the tests are not yet FDA approved—they are being used under an "investigational new drug" (IND) designation—the agency says it has sufficient data that the tests "perform appropriately in this setting."
What happens if I test positive? If you donate blood, and you test positive for Zika, your results will be reported back to you and officials in your local health department and the Centers for Disease Control and Prevention, who will interview you to determine whether your infection was travel-related, sexually-transmitted, or locally-acquired. You will be blocked from donating blood for at least 120 days, and advised to consult a doctor if you are pregnant, or trying to become pregnant.
What if I need a transfusion? The U.S. blood supply is believed to be safe, because universal testing has been in place in affected regions. There have been cases of Zika transmission through blood transfusion, though, in Brazil. So if you are traveling to a Zika-affected area abroad, check in advance that the country you're visiting tests its blood supply for Zika. But given this uncertainty about blood-supply safety, pregnant women have yet another reason to avoid travel to Zika-affected countries.
