ABSTRACT
Background: This study sought to determine the prevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) nucleocapsid (N) and spike (S) protein immunoglobulin G (IgG) antibodies in healthcare and hospital workers (HCHWs), and changes in IgG N antibody levels over time. Methods: Longitudinal study of HCHWs at a freestanding, urban paediatric tertiary care hospital. Asymptomatic HCHWs aged ≥18 years working in clinical areas were eligible to enrol. Participants completed four surveys and blood draws over 12 months. Specimens were tested for IgG N at four timepoints and IgG S at 12 months. Results: In total, 531 HCHWs enrolled in this study; of these, 481 (91%), 429 (81%) and 383 (72%) completed follow-up blood draws at 2, 6 and 12 months, respectively. Five of 531 (1%), 5/481 (1%), 6/429 (1%) and 5/383 (1.3%) participants were seropositive for IgG N at baseline, 2, 6 and 12 months, respectively. All (374/374; 100%) participants who received one or two doses of either mRNA COVID-19 vaccine were seropositive for IgG S. One of nine unvaccinated participants was seropositive for IgG S. Conclusions: In this paediatric hospital, IgG N and IgG S were detected in 1.9% and 97.9% of HCHWs, respectively. This study demonstrated low transmission of SARS-CoV-2 among HCHWs with appropriate infection prevention measures.
ABSTRACT
OBJECTIVES: Asymptomatic transmission of coronavirus disease 2019 (COVID-19) in health care settings is not well understood. In this study, we aimed to determine the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) antibodies in health care and hospital workers (HCHWs) and assess how antibody levels change over time. METHODS: Cross-sectional study of employed HCHWs at a freestanding, urban pediatric tertiary care hospital. Employed HCHWs ≥18 years old who were asymptomatic and worked in clinical hospital locations were eligible to participate. Participants completed blood draws and surveys at baseline (between May 4, 2020, and June 2, 2020) and 2 months later (between July 6, 2020, and August 7, 2020). Surveys collected demographic information, SARS-CoV-2 exposures, and previous COVID-19 diagnosis. RESULTS: In total, 530 participants enrolled in and completed baseline study activities. The median age was 37 years (range 19-67 years); 86% identified as female, and 80% identified as white. Two months later, 481 (91%) HCHWs completed another survey and blood draw. Four of 5 (0.9%) seropositive subjects at baseline remained seropositive at 2 months, although 3 had decreasing IgG indices. Five (1.0%) seropositive individuals, including 4 who were previously seropositive and 1 newly seropositive, were detected 2 months later. History of positive SARS-CoV-2 polymerase chain reaction testing results (P < .001) and history of COVID-19 exposure (P < .001) were associated with presence of SARS-CoV-2 antibodies. CONCLUSIONS: SARS-CoV-2 antibodies were detected in 1% of HCHWs in an urban pediatric hospital in a city with moderate SARS-CoV-2 prevalence. Participants with a known previous COVID-19 diagnosis showed a decline or loss of IgG antibodies over 2 months. These results have implications for identifying those with previous exposure and for ongoing public health recommendations for ensuring workplace safety.