Skip to main content


Nash, Denis; Srivastava, Avantika; Shen, Jenny; Penrose, Kate; Kulkarni, Sarah Gorrell; Zimba, Rebecca; You, William; Berry, Amanda; Mirzayi, Chloe; & Maroko, Andrew, et al. (Preprint). Seroincidence of SARS-COV-2 Infection Prior to and during the Rollout of Vaccines in a Community-Based Prospective Cohort of U.S. Adults. medRxiv. PMCID: PMC10593054


BACKGROUND: Infectious disease surveillance systems, which largely rely on diagnosed cases, underestimate the true incidence of SARS-CoV-2 infection, due to under-ascertainment and underreporting. We used repeat serologic testing to measure N-protein seroconversion in a well-characterized cohort of U.S. adults with no serologic evidence of SARS-CoV-2 infection to estimate the incidence of SARS-CoV-2 infection and characterize risk factors, with comparisons before and after the start of the SARS-CoV-2 vaccine and variant eras.
METHODS: We assessed the incidence rate of infection and risk factors in two sub-groups (cohorts) that were SARS-CoV-2 N-protein seronegative at the start of each follow-up period: 1) the pre-vaccine/wild-type era cohort (n=3,421), followed from April to November 2020; and 2) the vaccine/variant era cohort (n=2,735), followed from November 2020 to June 2022. Both cohorts underwent repeat serologic testing with an assay for antibodies to the SARS-CoV-2 N protein (Bio-Rad Platelia SARS-CoV-2 total Ab). We estimated crude incidence and sociodemographic/epidemiologic risk factors in both cohorts. We used multivariate Poisson models to compare the risk of SARS-CoV-2 infection in the pre-vaccine/wild-type era cohort (referent group) to that in the vaccine/variant era cohort, within strata of vaccination status and epidemiologic risk factors (essential worker status, child in the household, case in the household, social distancing).
FINDINGS: In the pre-vaccine/wild-type era cohort, only 18 of the 3,421 participants (0.53%) had


Reference Type

Journal Article

Year Published


Journal Title



Nash, Denis
Srivastava, Avantika
Shen, Jenny
Penrose, Kate
Kulkarni, Sarah Gorrell
Zimba, Rebecca
You, William
Berry, Amanda
Mirzayi, Chloe
Maroko, Andrew
Parcesepe, Angela M.
Grov, Christian
Robertson, McKaylee M.

Article Type





United States






Parcesepe - 0000-0002-4321-125x