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

Abstract

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.

Impact of FDA’s HCT/P ZIKV Recommendations on Cord Blood Unit Eligibility and Utilization in a Large Public Cord Blood Bank

“…These CBUs were discarded and not used in transplant. 19 , 20 Another study by the National Cord Blood Program, a public CBB, at New York Blood Center found that 27.5% of units collected from March 2016-December 2018 were ineligible for licensure, and, of these, 76% CBUs were ineligible due to ZIKV-related risk factors. 19 , 21 Of the 196 respondents to a 1-year follow-up survey sent to donors who had ZIKV risk, all mothers reported their infants were healthy.…”

Zika virus and its implications on cord blood banking and transplantation

“…The first study demonstrated that 25 of 875 mothers (2.9%) in Canada who donated their infant's cord blood had at least one risk factor for ZIKV exposure. However, none of the women had a documented ZIKV diagnosis during their pregnancies, and none of these UCB units were transplanted (all were discarded) . The second study, conducted by the New York Blood Center, showed that 27.5% of 4153 UCB units from March 2016 to December 2018 were from ineligible donors.…”