Alliance for Pandemic Preparedness

April 20, 2021

Identification of Natural SARS-CoV-2 Infection in Seroprevalence Studies among Vaccinated Populations

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  • [Pre-print, not peer-reviewed] Anti-nucleocapsid protein (N) antibodies were found to be an accurate method for differentiating between antibodies produced by natural infection and antibodies produced in response to vaccination, according to a study of healthcare workers (n=82). Participants were tested for anti-spike (S) IgG antibodies and anti-N IgG at two time points. No participants were vaccinated prior to the first time point and 46% reported vaccination by the second time point. Anti-spike antibodies were detectable prior to vaccination in 9.5% of participants. Among those with no prior infection at the second assay, anti-N levels were not significantly different by vaccination status whereas anti-S1 and S2 levels were elevated among vaccinated individuals. In contrast, anti-S1, S2, and N IgG levels were significantly elevated among infected vs uninfected individuals regardless of vaccination status. [EDITORIAL NOTE: Details on which vaccine participants received was not included but presumably were one of the EUA-approved vaccines in the US, all of which do not include a nucleocapsid insert. These data may not apply to all vaccines.]

Demmer et al. (Apr 19, 2021). Identification of Natural SARS-CoV-2 Infection in Seroprevalence Studies among Vaccinated Populations. Pre-print downloaded Apr 20 from https://doi.org/10.1101/2021.04.12.21255330