Zika and the Blood Supply: A Work in Progress.

Zika virus can be transmitted by transfusion, but the harm caused to recipients is not clear in most cases. It is very likely that the virus could also be transmitted by transplanted organs. Sensitivity to the risk from transfusion is elevated by consideration of possible severe neurologic damage in fetuses. Strategies for dealing with transfusion risk vary with the presence of Zika in the region. In nonendemic areas, risks can be reduced by excluding donors who have exposure through travel or sexual contact with someone at risk. In both endemic and nonendemic areas, the risk can be further reduced by nucleic acid testing of donors, or pathogen reduction of platelet and plasma products. The real risk to the population depends on the frequency of infection as well as the efficacy of these interventions. The interventions chosen will depend on the risk assessment for any situation; in the United States at this time, a combination of travel deferrals, testing, and, to a lesser extent, pathogen reduction is being used, but universal testing of US blood donors under investigational use has been mandated by the US Food and Drug Administration, beginning with states most at risk of local transmission. Canada is largely using travel deferrals. A precautionary approach may be taken; however, a formal decision-making framework has been suggested. The situation globally is clearly very fluid, as the epidemic continues to spread and we continue to learn how to best protect recipients of blood and transplants.