The US Food and Drug Administration (FDA) issued an additional safety measure against the emerging Zika virus outbreak. The agency issued a new guidance for immediate implementation providing recommendations to reduce the potential transmission risk of Zika virus from human cells, tissues, and cellular and tissue-based products (HCT/Ps). The guidance addresses donation of HCT/Ps from both living and deceased donors, including donors of umbilical cord blood, placenta, or other gestational tissues.

The new guidance is a part of the FDA’s ongoing efforts to protect HCT/Ps and blood products from Zika virus transmission. On February 16, the FDA issued recommendations for reducing the risk of Zika virus via blood transfusion in the US.

“Though there is more to be learned about the transmission of Zika virus, given what we know about the virus at this point, which also is informed by our understanding of similar viruses, we must address the potential risk of Zika virus transmission by human cells and tissues,” said Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research. “Providing HCT/P establishments with donor eligibility recommendations will help reduce that potential risk.”

There is a potential risk that the Zika virus can be transmitted by HCT/Ps used as part of a medical, surgical, or reproductive procedure. HCT/Ps include products such as corneas, bone, skin, heart valves, hematopoietic stem/progenitor cells (HPCs), gestational tissues such as amniotic membrane, and reproductive tissues such as semen and oocytes.

According to the Centers for Disease Control and Prevention, Zika virus can be spread by a man to his sexual partners. And to date, there have been several cases of sexual transmission in the US. Current information about Zika virus detection in semen suggests that a period of ineligibility longer than the waiting period that has been recommended for donors of Whole Blood and blood components is necessary for HCT/P donors.

Recommendations for living donors of HCT/Ps: Donors should be considered ineligible if they were diagnosed with Zika virus infection, were in an area with active Zika virus transmission, or had sex with a male with either of those risk factors, within the past six months. Donors of umbilical cord blood, placenta, or other gestational tissues should be considered ineligible if they have had any of the above risk factors at any point during their pregnancy.

Recommendations for deceased (non-heart-beating) donors: Donors should be considered ineligible if they were diagnosed with Zika virus infection in the past six months.

A deferral period of six months was chosen because of the limited data available on the length of time the virus can persist in all tissues. Zika virus has been detected in tissues and body fluids after the virus is no longer detectable in the blood stream, and has been detected in semen possibly up to 10 weeks after the onset of symptoms. Given the uncertainty, six months was determined to provide the appropriate level of caution.

Less evidence exists regarding the potential for transmission of Zika virus by HCT/Ps typically recovered from deceased donors. As more information becomes available, the understanding of the risks to recipients of HCT/Ps, including HCT/Ps recovered from deceased donors, may evolve. The FDA will continue to monitor the situation, and will carefully evaluate new information regarding the associated risks as it becomes available.

In addition to the guidance documents addressing the nation’s blood supply and HCT/Ps, the FDA continues to prioritize the development of blood donor screening and diagnostic tests that may be useful for identifying the presence of or recent infection with the virus, prepare to evaluate the safety and efficacy of investigational vaccines and therapeutics that might be developed, and review technology that may help suppress populations of the mosquitoes that can spread the virus.