Abstract
We analyzed 21 676 residual specimens from Ontario, Canada collected March-August 2020 to investigate the effect of antibody decline on SARS-CoV-2 seroprevalence estimates. Testing specimens orthogonally using Abbott (anti-nucleocapsid) and Ortho (anti-spike) assays, seroprevalence estimates were 0.4%-1.4%, despite ongoing disease activity. The geometric mean concentration (GMC) of antibody-positive specimens decreased over time (P = .015), and GMC of antibody-negative specimens increased over time (P = .0018). Association between the 2 tests decreased each month (P < .001), suggesting anti-nucleocapsid antibody decline. Lowering Abbott antibody index cutoff from 1.4 to 0.7 resulted in a 16% increase in positive specimens.
Keywords: COVID-19; SARS-CoV-2; serology; seroprevalence.
【저자키워드】 COVID-19, SARS-CoV-2, serology, Seroprevalence, 【초록키워드】 serology, antibody, Testing, SARS-CoV-2 seroprevalence, estimate, Canada, estimates, specimens, Anti-spike, Disease activity, Abbott, geometric mean, specimen, Cutoff, geometric mean concentration, lowering, positive, GMC, analyzed, collected, assays, increase in, 【제목키워드】 survey, Seroprevalence, estimate, Decline,