Just Say No?
Donors often visit places where infections not (yet?) endemic in the US are spreading. Dengue and chikungunya viruses are the current hotties, with Zika and Ross River viruses coming on strong. Each of these viruses, like West Nile virus, is characterized by asymptomatic viremia - the virus circulating in the blood before any illness - for several days, which may pose a transfusion risk. Potential exposures to malaria exclude many such donors, but nowhere near all of them. A short deferral of 14-28 days after return from international travel will get these donors past the risk. Can we do it? Asked more directly, how would such a deferral affect the blood supply?
Under the auspices of the AABB's Transfusion Transmitted Diseases Committee, investigators from American Red Cross and America's Blood Centers developed and have distributed anonymous, self-administered donor surveys about recent travel; many ABC centers participated. A paper survey in summer 2014 and a web-based survey in winter 2015 gathered information on destinations and intervals after return to the US and before donation. We measured the marginal impact on collections for different configurations of a travel deferral strategy.
More than 33,000 successful donors across nearly all 50 states completed the summer 2014 survey, with 2.6 percent reporting travel outside the US and Canada ≤28 days before donation. Mexico and Caribbean destinations accounted for >85 percent of travel in the Americas. A deferral of 28 days would affect 1.2 percent of donations during the summer, while limiting the deferral to 14 days reduced the impact to 0.4 percent. The winter 2015 survey (≈20,000 successful donors) found 4 percent reporting foreign travel within 28 days of donation and 1.4 percent reporting foreign travel outside of the US/Canada within 14 days of donation.
This population is potentially several-fold higher than the 0.5 to 0.75 percent of presenting donors currently deferred for potential malaria risk. A 28-day deferral encompassing all sites outside the US, Canada, and Western Europe might impact 2 to 4 percent of presenting donors annually, with modest regional variation. Two things will mitigate that effect. First, the deferral is much shorter than the malaria deferral. Second, it will be an extended implementation period to carefully educate donors that they need to wait an agreed-upon minimum interval after "getting off the boat" after international travel and before presenting to donate. The detailed survey results have been submitted as an abstract for the October 2015 AABB Annual Meeting.
This is a proactive approach to the proliferation of infections we should be thinking about (and responding to). It is in keeping with a focus on patient safety, and seems to have an easily manageable downside. Think about it.
Louis Katz, MD, Chief Medical Officer, email@example.com