SARS-CoV-2 Seroprevalence Survey Estimates Are Affected by Anti-Nucleocapsid Antibody Decline.

Shelly Bolotin, Vanessa Tran, Selma Osman, Kevin A Brown, Sarah A Buchan, Eugene Joh, Shelley L Deeks, Vanessa G Allen

The Journal of infectious diseases 2021 Apr 23

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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. © Her Majesty the Queen in Right of Canada, as represented by Ontario Agency for Health Protection and Promotion, 2021.

Citation

Shelly Bolotin, Vanessa Tran, Selma Osman, Kevin A Brown, Sarah A Buchan, Eugene Joh, Shelley L Deeks, Vanessa G Allen. SARS-CoV-2 Seroprevalence Survey Estimates Are Affected by Anti-Nucleocapsid Antibody Decline. The Journal of infectious diseases. 2021 Apr 23;223(8):1334-1338