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Testing for Zika Virus Among US Blood Donors

N Engl J Med; 2018 May 10; Saá, Proctor, et al

Screening blood donors in the US for Zika virus (ZIKV) by individual donation was costly and had a low yield, a recent study found. The American Red Cross implemented investigational screening of donated blood for ZIKV RNA by means of transcription-mediated amplification (TMA). Viral loads in plasma and red cells were estimated by means of end-point TMA. The costs of interdicting a donation that was confirmed to be positive were calculated for the 15-month period between June 2016 and September 2017. Researchers found:

  • Of the 4,325,889 donations that were screened, 393,713 (9%) were initially tested in 24,611 minipools, and no reactive donations were found.
  • Of the 3,932,176 donations that were subsequently tested individually, 160 were initially reactive and 9 were confirmed positive.
  • Among the 9 confirmed ZIKV-positive donations, only 4 were IgM-negative; of these donations, all 3 that were tested were reactive on minipool TMA.
  • The cost of identifying 8 mosquito-borne ZIKA infections through individual-unit nucleic acid testing was $5.3 million per ZIKA RNA-positive donation.


Saá P, Proctor M, Foster G, et al. Investigational testing for Zika virus among U.S. blood donors. N Engl J Med. 2018;378:1778-1788. doi:10.1056/NEJMoa1714977.