Incidence of SARS-CoV-2 Seropositivity in Pediatric Healthcare Workers Prior to Widespread Vaccination: A Five-month Longitudinal Cohort Study

Objectives Determine SARS-CoV-2 IgG antibody incidence over time in unvaccinated pediatric healthcare workers (pHCWs). Design Prospective longitudinal cohort of unvaccinated pHCWs measuring 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 post-infection, and neutralization antibodies were evaluated. Log-linear Poisson regression models were used to estimate incidence. Results Of 642 initially enrolled, 390 pHCWs presented for at least one follow-up serology test after baseline analysis. 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 non-physician 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). Conclusion Incidence of seropositivity was 8.2%. Although seropositivity was higher among ED staff during early stages of the pandemic, this difference declined over time, likely due to universal adoption of personal protective equipment (PPE).