Risk of Exposure to Zika Virus and Impact on Cord Blood Banking and Adult Unrelated Donors in Hematopoietic Cell Transplantation: The Canadian Blood Services Experience

Zika virus has emerged as a potential threat to the Canadian blood supply system. Stem cell donors within Canadian Blood Services' Cord Blood Bank (CBB) and OneMatch Stem Cell and Marrow Network (OM) now undergo screening measures designed to reduce the risk of Zika virus transmission. The impact these screening measures have on cord blood and unrelated adult stem cell donations is currently unknown. Among 146 donor workups initiated by OM between July 2016 and May 2017, 102 were completed and 44 workups were canceled. There were 17 potential donors (11.6%) with a risk of Zika virus exposure identified by the donor questionnaire (13 completed, 4 canceled workups). None of the workups involved a donor diagnosed with confirmed Zika virus within the past 6 months. Only 1 of the 44 canceled workups (and only 1 of 4 cases with a risk of Zika transmission) was canceled because of the risk of Zika transmission, and a backup donor was selected. Canadian Blood Services' CBB identified 25 of 875 cord blood units (2.9%) from women who donated their infants' cord blood and underwent screening that otherwise met the initial cell number thresholds for banking and had at least 1 risk factor for exposure to Zika virus. No women were diagnosed with Zika virus at any point of their pregnancy. All 25 units were discarded. Unrelated donors at OM have a higher incidence of a risk of exposure to Zika virus compared with cord blood donors. Only rarely did transplant centers cancel donor workups due to potential Zika virus exposure. The impact of screening for Zika virus exposure risk on cord blood banking was minor. Continued vigilance and surveillance is recommended.