The FDA now has new guidelines for keeping the Zika virus out of the US blood supply.
The agency is asking people who recently traveled to affected countries to wait four weeks before donating blood.
This also applies to everyone who had sexual contact with those travelers.
Most people affected by Zika don’t show any symptoms, but doctors say the four-week wait should be enough for their immune systems to clear the virus.
Zika is currently spreading through Latin America, Central Africa and Southeast Asia.