The US Food and Drug Administration (FDA) has recommended that blood no longer be collected from regions where the Zika virus is circulating, and that blood needed for transfusions be obtained from areas of the United States without active transmission. The agency said blood banks can continue collecting and preparing platelets and plasma if an FDA-approved pathogen-reduction technology is used. Current pathogen-reduction technology is not approved to treat whole red blood.

The FDA also formally endorsed recommendations made by the American Association of Blood Banks that donors at risk for Zika virus be deferred from donating blood for weeks. Those people include those who have had symptoms suggestive of Zika virus during the previous four weeks, those who have had sexual contact with a person who has travelled to, or resided in, an area with active Zika virus transmission during the prior three months, and those who have travelled to areas with active transmission of Zika during the past four weeks.

While there have been no reports of Zika entering the US blood supply, the risk of blood transmission is considered likely based on scientific evidence of how Zika and similar viruses spread, the agency said. The FDA issued these guidelines to ensure that blood banks defer blood donations, since about four out of five of those infected do not show symptoms.

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