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

doi:10.1093/infdis/jiaa796

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

J Infect Dis. 2021 Apr 23;223(8):1334-1338. doi: 10.1093/infdis/jiaa796.

Authors

Shelly Bolotin^{1

2

3}, Vanessa Tran^{1

3}, Selma Osman¹, Kevin A Brown^{1

2}, Sarah A Buchan^{1

2}, Eugene Joh¹, Shelley L Deeks^{1

2}, Vanessa G Allen^{1

3}

Affiliations

¹ Public Health Ontario, Toronto, Ontario, Canada.
² Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
³ Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Antibodies, Viral / blood*
Antibodies, Viral / immunology*
COVID-19 / blood*
COVID-19 / immunology*
COVID-19 Serological Testing / methods
Canada
Coronavirus Nucleocapsid Proteins / immunology*
Cross-Sectional Studies
Humans
Phosphoproteins / immunology
SARS-CoV-2 / immunology*
Seroepidemiologic Studies
Spike Glycoprotein, Coronavirus / immunology

Substances

Antibodies, Viral
Coronavirus Nucleocapsid Proteins
Phosphoproteins
Spike Glycoprotein, Coronavirus
nucleocapsid phosphoprotein, SARS-CoV-2