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

Objectives: Determine SARS-CoV-2 IgG antibody incidence over time in unvaccinated pediatric healthcare workers (pHCWs).

Design: A 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.

Results: Of 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).

Conclusion: The 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.