Characterizing the asymptomatic spread of SARS-CoV-2 is important for understanding the COVID-19 pandemic. This study was aimed at determining asymptomatic spread of SARS-CoV-2 in a suburban, Southern U.S. population during a period of state restrictions and physical distancing mandates. This is one of the first published seroprevalence studies from North Carolina and included multicenter, primary care, and emergency care facilities serving a low-density, suburban and rural population since description of the North Carolina state index case introducing the SARS-CoV-2 respiratory pathogen to this population. To estimate point seroprevalence of SARS-CoV-2 among asymptomatic individuals over time, two cohort studies were examined. The first cohort study, named ScreenNC, was comprised of outpatient clinics, and the second cohort study, named ScreenNC2, was comprised of inpatients unrelated to COVID-19. Asymptomatic infection by SARS-CoV-2 (with no clinical symptoms) was examined using an Emergency Use Authorization (EUA)-approved antibody test (Abbott) for the presence of SARS-CoV-2 IgG. This assay as performed under CLIA had a reported specificity/sensitivity of 100%/99.6%. ScreenNC identified 24 out of 2,973 (0.8%) positive individuals among asymptomatic participants accessing health care during 28 April to 19 June 2020, which was increasing over time. A separate cohort, ScreenNC2, sampled from 3 March to 4 June 2020, identified 10 out of 1,449 (0.7%) positive participants.
IMPORTANCE This study suggests limited but accelerating asymptomatic spread of SARS-CoV-2. Asymptomatic infections, like symptomatic infections, disproportionately affected vulnerable communities in this population, and seroprevalence was higher in African American participants than in White participants. The low, overall prevalence may reflect the success of shelter-in-place mandates at the time this study was performed and of maintaining effective physical distancing practices among suburban populations. Under these public health measures and aggressive case finding, outbreak clusters did not spread into the general population.
CONTEXT: Since 1993, the Centers for Disease Control and Prevention and professional medical organizations have recommended that all sexually experienced female adolescents receive annual screening for Chlamydia trachomatis. Whether adolescents receive this care is largely unknown.
METHODS:Reports of receipt of testing or treatment for a sexually transmitted disease (STD) in the past year, as well as sites of care, were obtained from 3,987 sexually experienced females in grades 7-12 who participated in Wave 1 of the National Longitudinal Study of Adolescent Health, conducted in 1995. Logistic regression was used to determine predictors of reporting care.
RESULTS:Eighteen percent of all participants reported having received STD services in the past year. Of those who reported having had a routine physical examination in the past year, 22% reported receipt of STD services. The proportion reporting STD care increased linearly with age from 9% of 12-13-year-olds to 25% of those 19 or older. In adjusted analyses, the odds of reporting testing or treatment were elevated among participants who had had a physical examination in the past year (odds ratio, 2.1), those with Medicaid or Medicare insurance (1.9), black women (1.5) and older adolescents (1.2). Adolescents most often reported having received STD care at a community health center (44%) or a private physician's office (31%).
CONCLUSIONS:Continued inadequate screening may contribute to persisting high prevalence of chlamydia infection among adolescents. Future research is needed to determine whether the proportions of adolescents receiving recommended STD screening have increased over time.
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