Cumulative incidence of SARS-CoV-2 infections among adults in Georgia, USA, August-December 2020 (preprint)

Background: Reported COVID-19 cases underestimate the true number of SARS-CoV-2 infections. Data on all infections, including asymptomatic infection, are needed to guide state testing and prevention programs. To minimize biases in estimates from seroprevalence surveys and reported cases, we conducted a state-wide probability survey of Georgia households and estimated cumulative incidence of SARS-CoV-2 infections adjusted for antibody waning. Methods: From August to December 2020, we mailed kits to self-collect specimens (nasal swabs and blood spots) to a random sample of Georgia addresses. One randomly-selected adult household member completed a survey and returned specimens for virus and antibody testing. We estimated cumulative incidence of SARS-CoV-2 infections adjusted for waning antibodies, reported fraction, and infection fatality ratio (IFR). Differences in seropositivity among demographic, geographic and clinical subgroups were explored with weighted prevalence ratios (PR). Results: Among 1,370 Georgia adult participants, adjusted cumulative incidence of SARS-CoV-2 was 16.1% (95% credible interval (CrI): 13.5-19.2%) as of November 16, 2020. The reported fraction was 26.6% and IFR was 0.78%. Non-Hispanic Black (PR: 2.03, CI 1.0, 4.1) and Hispanic adults (PR: 1.98, CI 0.74, 5.31) were more likely than non-Hispanic White adults to be seropositive. Seropositivity in metropolitan Atlanta's Fulton and DeKalb counties was similar to seropositivity elsewhere in Georgia (7.8% vs. 8.8%). Conclusions: As of mid-November 2020, one in 6 adults in Georgia had been infected with SARS-CoV-2. The scope of the COVID-19 epidemic in Georgia is likely substantially underestimated by reported cases.

Estimating the cumulative incidence of SARS-CoV-2 infection and the infection fatality ratio in light of waning antibodies (preprint)

Background: Serology tests can identify previous infections and facilitate estimation of the number of total infections. However, immunoglobulins targeting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported to wane below the detectable level of serological assays. We estimate the cumulative incidence of SARS-CoV-2 infection from serology studies, accounting for expected levels of antibody acquisition (seroconversion) and waning (seroreversion), and apply this framework using data from New York City (NYC) and Connecticut. Methods: We estimated time from seroconversion to seroreversion and infection fatality ratio (IFR) using mortality data from March-October 2020 and population-level cross-sectional seroprevalence data from April-August 2020 in NYC and Connecticut. We then estimated the daily seroprevalence and cumulative incidence of SARS-CoV-2 infection. Findings: The estimated average time from seroconversion to seroreversion was 3-4 months. The estimated IFR was 1.1% (95% credible interval: 1.0-1.2%) in NYC and 1.4% (1.1-1.7%) in Connecticut. The estimated daily seroprevalence declined after a peak in the spring. The estimated cumulative incidence reached 26.8% (24.2-29.7%) and 8.8% (7.1-11.3%) at the end of September in NYC and Connecticut, higher than maximum seroprevalence measures (22.1% and 6.1%), respectively. Interpretation: The cumulative incidence of SARS-CoV-2 infection is underestimated using cross-sectional serology data without adjustment for waning antibodies. Our approach can help quantify the magnitude of underestimation and adjust estimates for waning antibodies. Funding: This study was supported by the US National Science Foundation and the National Institute of Allergy and Infectious Diseases.

Changes in sexual behavior, PrEP adherence, and access to sexual health services due to the COVID-19 pandemic among a cohort of PrEP-using MSM in the South (preprint)

BackgroundThe COVID-19 pandemic has had unforeseen consequences on the delivery of HIV and STD prevention services. However, little is known about how the pandemic has impacted PrEP-using men who have sex with men (MSM). MethodsData come from an online cohort of PrEP-using MSM in the Southern United States from October 2019 to July 2020. Participants were administered ten surveys in total, including one ad hoc survey specifically on COVID-19. We conducted a cross-sectional analysis of this ad hoc survey (n=56) and present changes in sexual behaviors and utilization of and access to sexual health services. Using linear mixed-effects regression models, we also analyzed data from the larger cohort (n=78) and document how sexual behaviors and PrEP use varied longitudinally focusing on three months: February (pre-pandemic), April (early pandemic), and June (later in the pandemic). ResultsA fifth of participants discontinued or changed how often they take PrEP because of COVID-19. A quarter of the cohort documented challenges when attempting to access PrEP, HIV testing, or STD testing. For all sexual behaviors examined longitudinally--number of male sexual partners, anal sex acts, condomless anal sex, oral sex (all measured in the past 2 weeks)--there was a significant decrease from February to April followed by a significant increase from April to June. DiscussionOur findings suggest reduced access to and utilization of STD and HIV services coupled with a continuation of behaviors which confer STD/HIV risk. Ensuring appropriate delivery of STD/HIV prevention services during this pandemic is imperative.

Early Release Estimates for SARS-CoV-2 Prevalence and Antibody Response Interim Weighting for Probability-Based Sample Surveys (preprint)

Many months into the SARS-CoV-2 pandemic, basic epidemiologic parameters describing burden of disease are lacking. To reduce selection bias in current burden of disease estimates derived from diagnostic testing data or serologic testing in convenience samples, we are conducting a national probability-based sample SARS-CoV-2 serosurvey. Sampling from a national address-based frame and using mailed recruitment materials and test kits will allow us to estimate national prevalence of SARS-CoV-2 infection and antibodies, overall and by demographic, behavioral, and clinical characteristics. Data will be weighted for unequal selection probabilities and non-response and will be adjusted to population benchmarks. Due to the urgent need for these estimates, expedited interim weighting of serosurvey responses will be undertaken to produce early release estimates, which will be published on the study website, COVIDVu.org. Here, we describe a process for computing interim survey weights and guidelines for release of interim estimates.

At-home self-collection of saliva, oropharyngeal swabs and dried blood spots for SARS-CoV-2 diagnosis and serology: post-collection acceptability of specimen collection process and patient confidence in specimens (preprint)

Background: Options to increase the ease of testing for SARS-CoV-2 infection and immune response are needed. Self-collection of diagnostic specimens at home offers an avenue to allow people to test for SARS-CoV-2 infection or immune response without traveling to a clinic or laboratory. Before this study, survey respondents indicated willingness to self-collect specimens for COVID-related tests, but hypothetical willingness can differ from post-collection acceptability after participants collect specimens. Methods: 153 US adults were enrolled in a study of the willingness and feasibility of patients to self-collect three diagnostic specimens (saliva, oropharyngeal swab (OPS) and dried blood spot (DBS) card) while observed by a clinician through a telehealth session. After the specimens were collected, 148 participants participated in a survey about the acceptability of the collection, packing and shipping process, and their confidence in the samples collected for COVID-related laboratory testing. Results: A large majority of participants (>84%) reported that collecting, packing and shipping of saliva, OPS, and DBS specimens were acceptable. Nearly nine in 10 (87%) reported being confident or very confident that the specimens they collected were sufficient for laboratory analysis. There were no differences in acceptability for any specimen type, packing and shipping, or confidence in samples by gender, age, race/ethnicity, or educational level. Conclusions: Self-collection of specimens for SARS-CoV-2 testing and preparing and shipping specimens for analysis were acceptable in a diverse group of US adults. Further refinement of materials and instructions to support self-collection of saliva, OPS and DBS specimens for COVID-related testing is needed.

Willingness to seek laboratory testing for SARS-CoV-2 with home, drive-through, and clinic-based specimen collection locations (preprint)

BackgroundSARS-CoV-2 virus testing for persons with COVID-19 symptoms, and contact tracing for those testing positive, will be critical to successful epidemic control. Willingness of persons experiencing symptoms to seek testing may determine the success of this strategy. MethodsA cross-sectional, online survey in the United States measured willingness to seek testing if feeling ill under different specimen collection scenarios: home-based saliva, home-based swab, drive-through facility swab, and clinic-based swab. Instructions clarified that home-collected specimens would be mailed to a laboratory for testing. We presented similar willingness questions regarding testing during follow-up care. ResultsOf 1435 participants, comprising a broad range of sociodemographic groups, 92% were willing to test with a home saliva specimen, 88% with home swab, 71% with drive-through swab, and 60% with clinic collected swab. Moreover, 68% indicated they would be more likely to get tested if there was a home testing option. There were no significant differences in willingness items across sociodemographic variables or for those currently experiencing COVID-19 symptoms. Results were nearly identical for willingness to receive testing for follow-up COVID-19 care. ConclusionsWe observed a hierarchy of willingness to test for SARS-CoV-2, ordered by the degree of contact required. Home specimen collection options could result in up to one-third more symptomatic persons seeking testing, facilitating contact tracing and optimal clinical care. Remote specimen collection options may ease supply chain challenges and decrease the likelihood of nosocomial transmission. As home specimen collection options receive regulatory approval, they should be scaled rapidly by health systems.