Incidence of SARS-CoV-2 seropositivity in pediatric healthcare workers prior to widespread vaccination: A 5-month longitudinal cohort study

Abstract

ObjectivesDetermine SARS-CoV-2 IgG antibody incidence over time in unvaccinated pediatric healthcare workers (pHCWs). DesignA prospective longitudinal cohort of unvaccinated pHCWs measuring the incidence of new infection after initial prevalence was established at 4.1% with seropositive predominance in emergency department (ED)-based pHCWs. Serum samples were collected at follow-up visits to detect new SARS-CoV-2 seropositivity. Univariate analysis was performed to estimate different incidence rates between participant demographics, job, employment location, and community risk factors. Anxiety levels about COVID-19 were collected. SARS-CoV-2 antibody decay postinfection and neutralization antibodies were evaluated. Log-linear Poisson regression models were used to estimate incidence. ResultsOf 642 initially enrolled, 390 pHCWs presented for at least one follow-up serology test after baseline analysis. The incidence of SARS-CoV-2 seropositivity was 8.2%. The seropositive cohort, like the negative one, consisted mainly of females in non-ED settings and nonphysician roles. There were no statistically significant differences in incidence across variables. Seropositive participants dropped antibody titers by 50% at 3 months. Neutralization antibodies correlated to SARS-CoV-2 binding antibodies (r = 0.43, P < 0.0001). ConclusionThe incidence of seropositivity was 8.2%. Although seropositivity was higher among ED staff during the early stages of the pandemic, this difference declined over time, likely due to the universal adoption of personal protective equipment.