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. 2022 Jan 25:M21-3272. doi: 10.7326/M21-3272

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Figure. — The evidence search and assessment were conducted by the Portland VA Research Foundation (3, 5, 6). The evidence search was updated through 22 September 2021. PCR = polymerase chain reaction.

* Observational studies include studies estimating seroprevalence among a given population that includes a small subpopulation known to have SARS-CoV-2 infection; cross-sectional or cohort studies characterizing the antibody response among adults with SARS-CoV-2 infection; and large, population-based observational (cohort, case–control) studies comparing risk for reinfection in adults with and without recent SARS-CoV-2 infection (3,5,6). Immunoassay validation studies include those validating the diagnostic performance of 1 or more immunoassays (3).