Anti sars cov 2 nucleocapsid

Samples analyzed in this study were from the COVID-19 Occupational Risks, Seroprevalence and Immunity Among Paramedics in Canada (CORSIP) study (collected January 25, 2021 to July 14, 2021), approved by the University of British Columbia (H20-03620) and University of Toronto (40435) research ethics boards. The CORSIP study is a prospective observational cohort of adult paramedics in Canada, who provided blood samples at enrollment and 6 months (+/–10 days) after their first SARS-CoV-2 vaccine. Participants provided informed written consent, and completed sociodemographic and health questionnaires, including vaccination status and PCR/rapid antigen testing history.
This study was a post hoc analysis of samples that were tested with multiple serological assays and for live virus neutralizing antibody titers (18 (link)). Samples were eligible if the participant had never received a diagnosis of COVID-19 and had two doses of the same mRNA vaccine (either BNT162b2 or mRNA-1273), and the sample was nonreactive on an Elecsys Anti-SARS-CoV-2 nucleocapsid (Roche, IN, USA) assay (19 (link)) to confirm absence of prior SARS-CoV-2 infection.

For this analysis, we included participants who received two doses of the BNT162b2 vaccine or two doses of the mRNA-1273 vaccine, and provided a blood sample 170 to 190 days after the first vaccine dose. We excluded individuals with previous COVID-19, defined as a positive NAAT test or a reactive test on the Elecsys Anti-SARS-CoV-2 nucleocapsid (Roche, IND, USA; see supplemental materials) assay (which is indicative of prior SARS-CoV-2 infection rather than vaccination).