Methods| The sampling, laboratory, and analytic methods were identical to those in the
studies conducted in 2020. 2, 3 Plasma samples with complete donor demographic data
and sufficient volume collected from all 6 regional transfusion centers were included and
assayed for anti–spike IgG using an enzymelinked immunosorbent assay. Validated among
910 prepandemic serum samples from coastal Kenya and 174 patients with positive
polymerase chain reaction test results from Nairobi, specificity was 99.0% and sensitivity …