Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Prevalence and Associated Risk Factors in a Large Cohort of US Children.

Background: Household transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may play a key role in times of increased infection, particularly among children. We aimed to determine the prevalence of SARS-CoV-2 antibodies and identify risk factors associated with SARS-CoV-2 antibody positivity in children.

Methods: Unvaccinated children aged 18 months to 11 years between August 2022 and June 2023 underwent oral fluid testing for SARS-CoV-2 antibodies. Caregivers completed electronic surveys at 4 major healthcare practices in Northern and Central New Jersey. Information was collected on demographics, household size, vaccination status, and prior SARS-CoV-2-related illness. Multivariable logistic regression determined individual and household-level factors associated with SARS-CoV-2 antibody positivity.

Results: A total of 870 children provided tests and corresponding surveys. Children were predominantly Hispanic (37%) or non-Hispanic Black (30%), and on average 5.7 years old. Overall SARS-CoV-2 antibody positivity was 68%. Risk factors for SARS-CoV-2 positivity include Hispanic or non-Hispanic Black race/ethnicity (adjusted odds ratios [aOR], 2.29 and 1.95 vs. White race/ethnicity; P < .01) and later enrollment in the study period. Children from households with ≥1 vaccinated adult were 52% less likely to be antibody positive than those from households with no vaccinated adults (aOR: 0.38, [95% confidence interval 0.2 to 0.69]).

Conclusions: There is high burden of SARS-CoV-2 infection among children over time. Adult vaccination appears to be a protective factor in helping to mitigate coronavirus disease 2019 (COVID-19) infection among children. Increased vaccination of adults in the community can help inform COVID-19 prevention strategies for minors in the household.