ABSTRACT
COVID-19 is one of the largest public health emergencies in modern history. Here we present a detailed analysis from a large population center in Southern California (Orange County, population of 3.2 million) to understand heterogeneity in risks of infection, test positivity, and death. We used a combination of datasets, including a population-representative seroprevalence survey, to assess the true burden of disease as well as COVID-19 testing intensity, test positivity, and mortality. In the first month of the local epidemic, case incidence clustered in high income areas. This pattern quickly shifted, with cases next clustering in much higher rates in the north-central area which has a lower socio-economic status. Since April, a concentration of reported cases, test positivity, testing intensity, and seropositivity in a north-central area persisted. At the individual level, several factors (e.g., age, race/ethnicity, zip codes with low educational attainment) strongly affected risk of seropositivity and death.
ABSTRACT
BackgroundClinic-based estimates of SARS-CoV-2 may considerably underestimate the total number of infections. Access to testing in the US has been heterogeneous and symptoms vary widely in infected persons. Public health surveillance efforts and metrics are therefore hampered by underreporting. We set out to provide a minimally biased estimate of SARS-CoV-2 seroprevalence among adults for a large and diverse county (Orange County, CA, population 3.2 million). MethodsWe implemented a surveillance study that minimizes response bias by recruiting adults to answer a survey without knowledge of later being offered a SARS-CoV-2 test. Several methodologies were used to retrieve a population-representative sample. Participants (n=2,979) visited one of 11 drive-thru test sites from July 10th to August 16th, 2020 (or received an in-home visit) to provide a finger pin-prick sample. We applied a robust SARS-CoV-2 Antigen Microarray technology, which has superior measurement validity relative to FDA-approved tests. FindingsParticipants include a broad age, gender, racial/ethnic, and income representation. Adjusted seroprevalence of SARS-CoV-2 infection was 11.5% (95% CI: 10.5% to 12.4%). Formal bias analyses produced similar results. Prevalence was elevated among Hispanics (vs. other non-Hispanic: prevalence ratio [PR]= 1.47, 95% CI: 1.22 to 1.78) and household income <$50,000 (vs. >$100,000: PR= 1.42, 95% CI: 1.14 to 1.79). InterpretationResults from a diverse population using a highly specific and sensitive microarray indicate a SARS-CoV-2 seroprevalence of [~]12 percent. This population-based seroprevalence is seven-fold greater than that using official County statistics. In this region, SARS-CoV-2 also disproportionately affects Hispanic and low-income adults. FundingOrange County Healthcare Agency
ABSTRACT
Understanding SARS-CoV-2 antibody prevalence as a marker of prior infection in a spectrum of healthcare workers (HCWs) may guide risk stratification and enactment of better health policies and procedures. The present study reported on cross-sectional study to determine the prevalence and longevity of SARS-CoV-2 antibodies in HCWs at a regional hospital system in Orange County, California, between May and August, 2020. Data from HCWs (n=3,458) were included in the analysis. Data from first responders (n=226) were also analyzed for comparison. A blood sample was collected at study enrollment and 8-week follow-up. Information on job duties, location, COVID-19 symptoms, polymerase chain reaction test history, travel since January 2020, and household contacts with COVID-19 was collected. Comparisons to estimated community prevalence were also evaluated. Observed antibody prevalence was 0.93% and 2.58% at initial and 8-week follow-up, respectively, for HCWs, and 5.31% and 4.35% for first responders. For HCWs, significant differences (p < .05) between negative vs. positive at initial assessment were found for age, race, fever, and loss of smell, and at 8-week follow-up for age, race, and all symptoms. Antibody positivity persisted at least 8 weeks in this cohort. Among 75 HCWs with self-reported prior PCR-confirmed COVID-19, 35 (46.7%) were antibody negative. Significant differences between negative vs. positive were observed in age and frequency of symptoms. This study found considerably lower SARS-CoV-2 antibody prevalence among HCWs compared with prior published studies. This may be explained by better safety measures in the workplace, heightened awareness inside and outside of the workplace, possibly lower susceptibility due to innate immunity and other biological heterogeneity, and low COVID-19 prevalence in the community itself. HCWs with initial positive results had persistent positive serologies at 8 weeks. Further research is warranted to investigate factors influencing such lower prevalence in our HCWs.
ABSTRACT
SARS-CoV-2 has driven a pandemic crisis. Serological surveys have been conducted to establish prevalence for covid-19 antibody in various cohorts and communities. However, the prevalence among healthcare workers is still being analyzed. The present study reports on initial sero-surveillance conducted on healthcare workers at a regional hospital system in Orange County, California, during May and June, 2020. Study participants were recruited from the entire hospital employee workforce and the independent medical staff. Data were collected for job title, location, covid-19 symptoms, a PCR test history, travel record since January 2020, and existence of household contacts with covid-19. A blood sample was collected from each subject for serum analysis for IgG antibodies to SARS- CoV-2. Of 3,013 tested individuals, a total 2,932 were included in the analysis due to some missing data. Observed prevalence of 1.06% (31 antibody positive cases), adjusted prevalence of 1.13% for test sensitivity and specificity were identified. Significant group differences between positive vs. negative were observed for age (z = 2.65, p = .008), race (p = .037), presence of fever (p < .001) and loss of smell (p < .001). Possible explanation for this low prevalence includes a relatively low local geographic community prevalence ([~]4.4%) at the time of testing, the hospitals timely procurement of personal protective equipment, rigorous employee education, patient triage and treatment protocol development and implementation. In addition, possible greater presence of cross- reactive adaptive T cell mediated immunity in healthcare workers vs. the general population may have contributed. Determining antibody prevalence in front-line workers, and duration of antibody presence may help stratify the workforce for risk, establish better health place policies and procedures, and potentially better mitigate transmission.
ABSTRACT
BackgroundCoronavirus disease 2019 (COVID-19), the respiratory disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first identified in Wuhan, China and has since become pandemic. As part of initial response activities in the United States, enhanced contact investigations were conducted to enable early identification and isolation of additional cases and to learn more about risk factors for transmission. MethodsClose contacts of nine early travel-related cases in the United States were identified. Close contacts meeting criteria for active monitoring were followed, and selected individuals were targeted for collection of additional exposure details and respiratory samples. Respiratory samples were tested for SARS-CoV-2 by real-time reverse transcription polymerase chain reaction (RT-PCR) at the Centers for Disease Control and Prevention. ResultsThere were 404 close contacts who underwent active monitoring in the response jurisdictions; 338 had at least basic exposure data, of whom 159 had [≥]1 set of respiratory samples collected and tested. Across all known close contacts under monitoring, two additional cases were identified; both secondary cases were in spouses of travel-associated case patients. The secondary attack rate among household members, all of whom had [≥]1 respiratory sample tested, was 13% (95% CI: 4 - 38%). ConclusionsThe enhanced contact tracing investigations undertaken around nine early travel-related cases of COVID-19 in the United States identified two cases of secondary transmission, both spouses. Rapid detection and isolation of the travel-associated case patients, enabled by public awareness of COVID-19 among travelers from China, may have mitigated transmission risk among close contacts of these cases.
ABSTRACT
IntroductionMore than 93,000 cases of coronavirus disease (COVID-19) have been reported worldwide. We describe the epidemiology, clinical course, and virologic characteristics of the first 12 U.S. patients with COVID-19. MethodsWe collected demographic, exposure, and clinical information from 12 patients confirmed by CDC during January 20-February 5, 2020 to have COVID-19. Respiratory, stool, serum, and urine specimens were submitted for SARS-CoV-2 rRT-PCR testing, virus culture, and whole genome sequencing. ResultsAmong the 12 patients, median age was 53 years (range: 21-68); 8 were male, 10 had traveled to China, and two were contacts of patients in this series. Commonly reported signs and symptoms at illness onset were fever (n=7) and cough (n=8). Seven patients were hospitalized with radiographic evidence of pneumonia and demonstrated clinical or laboratory signs of worsening during the second week of illness. Three were treated with the investigational antiviral remdesivir. All patients had SARS-CoV-2 RNA detected in respiratory specimens, typically for 2-3 weeks after illness onset, with lowest rRT-PCR Ct values often detected in the first week. SARS-CoV-2 RNA was detected after reported symptom resolution in seven patients. SARS-CoV-2 was cultured from respiratory specimens, and SARS-CoV-2 RNA was detected in stool from 7/10 patients. ConclusionsIn 12 patients with mild to moderately severe illness, SARS-CoV-2 RNA and viable virus were detected early, and prolonged RNA detection suggests the window for diagnosis is long. Hospitalized patients showed signs of worsening in the second week after illness onset.
