Re‐examine the transfusion transmitted risk of SARS‐CoV‐2 virus during a major COVID‐19 outbreak in 2022

Introduction Although no case of COVID‐19 transmission through transfusion has been reported, blood transfusion service (BTS) continues to implement pre‐donation and post‐donation measures to minimise the risk. In year 2022, when local healthcare system was badly impacted by a major outbreak, it opened an opportunity to re‐examine the viraemia risk in these asymptomatic donors. Materials and Methods Records were retrieved from blood donors who reported COVID‐19 after donation and follow‐up was also made for recipients who received their blood. Blood samples at donation were tested for SARS‐CoV‐2 viraemia by single‐tube nested real‐time RT‐PCR assay designed to detect most SARS‐CoV‐2 variants including the prevailing delta and omicron variants. Results From 1 January to 15 August 2022, the city with 7.4 M inhabitants recorded 1 187 844 COVID‐19 positive cases and 125 936 successful blood donations were received. 781 donors reported to the BTS after donation with 701 being COVID‐19 related (including close contact and symptoms respiratory tract infection). 525 COVID‐19 were positive at the time of call back or follow‐up. Of the 701 donations, they were processed into 1480 components with 1073 discarded upon donors' call back. For remaining 407 components, no recipient was found to have adverse event or COVID‐19 positive. 510 samples from the above 525 COVID‐19 positive donors were available and all tested negative for SARS‐CoV‐2 RNA. Discussion With the negative SARS‐CoV‐2 RNA in blood donation samples and follow up data in transfusion recipients, the risk of transfusion transmitted COVID‐19 appears negligible. However, current measures remains important in securing blood safety with ongoing surveillance of their effectiveness.