Surveillance of SARS-CoV-2 Antibodies in Early 2020 among Rhode Island Pregnancies.

ABSTRACT

OBJECTIVE: Limited data are available on the performance of SARS-CoV-2 antibody assays and data collected during pregnancy vary widely. The objective of this study was to estimate the seroprevalence of antibodies against SARS-CoV-2 in pregnant individuals in Rhode Island and to evaluate whether the prevalence differed by month of collection, age, county of residence, or economic status as estimated by zip code. METHODS: Pre-pandemic (2019) and early pandemic (2020) serum samples, collected for prenatal screening between 15 and 22 weeks of gestation, were analyzed utilizing two SARS-CoV-2 immunoglobulin G (IgG) automated assays that targeted the viral nucleocapsid (anti-N) or spike (anti-S) receptor binding domain proteins. RESULTS: Among 756 pre-pandemic samples, one anti-S IgG and 13 anti-N IgG were identified. No samples were positive for both. Among 787 pandemic specimens, 16 (2.03%) were positive for both anti-N IgG and anti-S IgG. When stratified by month of collection, there was a significant increase in seropositivity rate (p=0.023). Seropositivity rates were associated with lower income levels (p=0.08) but this was not statistically significant. No trend by maternal age was found (p=0.70). CONCLUSIONS: When a positive result was defined as both anti-N IgG and anti-S IgG, false positives were unlikely. Based on this methodology, serology could be utilized to monitor infection trends during pregnancy.