SARS-CoV-2 active infection prevalence and seroprevalence in the adult population of St. Louis County.

BACKGROUND: The true prevalence of COVID-19 is difficult to estimate due to the absence of random population-based testing. To estimate current and past COVID-19 infection prevalence in a large urban area, we conducted a population-based survey in St. Louis County, Missouri. METHODS: The population-based survey of active infection (PCR) and seroprevalence (IgG antibodies) of adults (≥18 years) was conducted through random-digit dialing and targeted sampling of St. Louis County residents with oversampling of Black residents. Infection prevalence of residents was estimated using design-based and raking weighting. RESULTS: Between August 17 and October 24, 2020, 1245 residents completed a survey and underwent PCR testing; 1073 residents completed a survey and underwent PCR and IgG testing or self-reported results. Weighted prevalence estimates of residents with active infection were 1.9% (95% CI, 0.4%-3.3%) and 5.6% were ever infected (95% CI, 3.3%-8.0%). Overall infection hospitalization and fatality ratios were 4.9% and 1.4%, respectively. CONCLUSIONS: Through October 2020, the percentage of residents that had ever been infected was relatively low. A markedly higher percentage of Black and other minorities compared to White residents were infected with COVID-19. The St. Louis region remained highly vulnerable to widespread infection in late 2020.

Severe Acute Respiratory Syndrome Coronavirus 2 Cumulative Incidence, United States, August 2020-December 2020.

BACKGROUND: Reported coronavirus disease 2019 (COVID-19) cases underestimate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. We conducted a national probability survey of US households to estimate cumulative incidence adjusted for antibody waning. METHODS: From August-December 2020 a random sample of US addresses were mailed a survey and self-collected nasal swabs and dried blood spot cards. One adult household member completed the survey and mail specimens for viral detection and total (immunoglobulin [Ig] A, IgM, IgG) nucleocapsid antibody by a commercial, emergency use authorization-approved antigen capture assay. We estimated cumulative incidence of SARS-CoV-2 adjusted for waning antibodies and calculated reported fraction (RF) and infection fatality ratio (IFR). Differences in seropositivity among demographic, geographic, and clinical subgroups were explored. RESULTS: Among 39 500 sampled households, 4654 respondents provided responses. Cumulative incidence adjusted for waning was 11.9% (95% credible interval [CrI], 10.5%-13.5%) as of 30 October 2020. We estimated 30 332 842 (CrI, 26 703 753-34 335 338) total infections in the US adult population by 30 October 2020. RF was 22.3% and IFR was 0.85% among adults. Black non-Hispanics (Prevalence ratio (PR) 2.2) and Hispanics (PR, 3.1) were more likely than White non-Hispanics to be seropositive. CONCLUSIONS: One in 8 US adults had been infected with SARS-CoV-2 by October 2020; however, few had been accounted for in public health reporting. The COVID-19 pandemic is likely substantially underestimated by reported cases. Disparities in COVID-19 by race observed among reported cases cannot be attributed to differential diagnosis or reporting of infections in population subgroups.

Population-Based Estimates of Post-acute Sequelae of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection (PASC) Prevalence and Characteristics.

BACKGROUND: Emerging evidence suggests many people have persistent symptoms after acute coronavirus disease 2019 (COVID-19) illness. Our objective was to estimate the prevalence and correlates of post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PASC). METHODS: We used a population-based probability survey of adults with COVID-19 in Michigan. Living noninstitutionalized adults aged ≥18 in the Michigan Disease Surveillance System with COVID-19 onset through mid-April 2020 were eligible for selection (N = 28 000). Among 2000 selected, 629 completed the survey between June-December 2020. We estimated PASC prevalence, defined as persistent symptoms ≥30 (30-day COVID-19) or ≥60 (60-day COVID-19) days post-COVID-19 onset, overall and by sociodemographic and clinical factors. We used modified Poisson regression to produce adjusted prevalence ratios (aPRs) for potential risk factors. RESULTS: The analytic sample (n = 593) was predominantly female (56.1%), aged ≥45 years (68.2%), and non-Hispanic White (46.3%) or Black (34.8%). Thirty- and 60-day COVID-19 were highly prevalent (52.5% and 35.0%), even among nonhospitalized respondents (43.7% and 26.9%) and respondents reporting mild symptoms (29.2% and 24.5%). Respondents reporting very severe (vs mild) symptoms had 2.25 times higher prevalence of 30-day COVID-19 (aPR, 2.25; 95% CI, 1.46-3.46) and 1.71 times higher prevalence of 60-day COVID-19 (aPR, 1.71; 95% CI: 1.02-2.88). Hospitalized (vs nonhospitalized) respondents had ~40% higher prevalence of both 30-day (aPR, 1.37; 95% CI: 1.12-1.69) and 60-day (aPR, 1.40; 95% CI: 1.02-1.93) COVID-19. CONCLUSIONS: PASC is highly prevalent among cases reporting severe initial symptoms and, to a lesser extent, cases reporting mild and moderate symptoms.