We estimated the trends and correlates of vaccine hesitancy, and its association with subsequent vaccine uptake among 5,458 adults in the United States. Participants belonged to the CHASING COVID Cohort, a national longitudinal study. Trends and correlates of vaccine hesitancy were examined longitudinally in eight interview rounds from October 2020 to July 2021. We also estimated the association between willingness to vaccinate and subsequent vaccine uptake through July 2021. Vaccine delay and refusal decreased from 51% and 8% in October 2020 to 8% and 6% in July 2021, respectively. Compared to Non-Hispanic (NH) White participants, NH Black and Hispanic participants had higher adjusted odds ratios (aOR) for both vaccine delay (aOR: 2.0 [95% CI: 1.5, 2.7] for NH Black and 1.3 [95% CI: 1.0, 1.7] for Hispanic) and vaccine refusal (aOR: 2.5 [95% CI: 1.8, 3.6] for NH Black and 1.4 [95% CI: 1.0, 2.0] for Hispanic) in June 2021. COVID-19 vaccine hesitancy was associated with lower odds of subsequent vaccine uptake (aOR: 0.15, 95% CI: 0.13, 0.18 for vaccine-delayers and aOR: 0.02; 95% CI: 0.01, 0.03 for vaccine-refusers compared to vaccine-willing participants), adjusted for sociodemographic factors and COVID-19 history. Vaccination awareness and distribution efforts should focus on vaccine delayers.

PurposeThe Communities, Households and SARS-CoV-2 Epidemiology (CHASING) COVID Cohort Study is a community-based prospective cohort study launched during the upswing of the USA COVID-19 epidemic. The objectives of the cohort study are to: (1) estimate and evaluate determinants of the incidence of SARS-CoV-2 infection, disease and deaths; (2) assess the impact of the pandemic on psychosocial and economic outcomes and (3) assess the uptake of pandemic mitigation strategies.ParticipantsWe began enrolling participants from 28 March 2020 using internet-based strategies. Adults≥18 years residing anywhere in the USA or US territories were eligible. 6740 people are enrolled in the cohort, including participants from all 50 US states, the District of Columbia, Puerto Rico and Guam. Participants are contacted regularly to complete study assessments, including interviews and dried blood spot specimen collection for serologic testing.Findings to dateParticipants are geographically and sociodemographically diverse and include essential workers (19%). 84.2% remain engaged in cohort follow-up activities after enrolment. Data have been used to assess SARS-CoV-2 cumulative incidence, seroincidence and related risk factors at different phases of the US pandemic; the role of household crowding and the presence of children in the household as potential risk factors for severe COVID-19 early in the US pandemic; to describe the prevalence of anxiety symptoms and its relationship to COVID-19 outcomes and other potential stressors; to identify preferences for SARS-CoV-2 diagnostic testing when community transmission is on the rise via a discrete choice experiment and to assess vaccine hesitancy over time and its relationship to vaccine uptake.Future plansThe CHASING COVID Cohort Study has outlined a research agenda that involves ongoing monitoring of the incidence and determinants of SARS-CoV-2 outcomes, mental health outcomes and economic outcomes. Additional priorities include assessing the incidence, prevalence and correlates of long-haul COVID-19.

Background Epidemiologic risk factors for incident SARS-CoV-2 infection are best characterized via prospective cohort studies, complementing case-based surveillance and cross-sectional seroprevalence studies. Methods We estimated the cumulative incidence of SARS-CoV-2 infection and incidence rates of seroconversion in a national prospective online cohort of 6,745 U.S. adults, enrolled March-July 2020. A subset (n=4,459) underwent serologic testing (Bio-Rad Platelia Total Ab, IgA/IgM/IgG), offered initially May-September 2020 and again November 2020-January 2021. Results A total of 303 of 4,459 individuals showed serologic evidence of past SARS-CoV-2 infection (cumulative incidence of 6.8%; 95% Confidence Interval [CI] 6.1%-7.6% [6.3%, 95% CI 5.7%-7.1% adjusting for laboratory test error]). Among 3,280 initially seronegative participants with a subsequent serologic test, we observed 145 seroconversions during 1,562 person years of follow-up (incidence rate of 9.3 per 100 person-years [95% CI 17.9-11.0]). Racial/ethnic disparities in crude incidence rates were apparent through January 2021 (rate ratio [RRHispanic vs Whites]=2.1; 95% CI 1.4-3.1; RRnon-Hispanic Blacks vs Whites=1.8; 95% CI 0.96-3.1). Incidence was higher in the southern (RRSouth vs Northeast=1.7; 95% CI 1.1-2.8) and midwestern (RRMidwest vs Northeast=1.6; 95% CI 0.98-2.7) regions, in rural vs urban areas (RR=1.5; 95% CI 1.0-2.2), and among essential workers (RR=1.7; 95% CI 1.1-2.5). Household crowding (RR=1.6, 95% CI 1.1-2.3), dining indoors at restaurants/bars (RR=2.0; 95% CI 1.4-2.8), visiting places of worship (RR=2.0; 95% CI 1.3-2.9), wearing masks sometimes vs always while grocery shopping (RR=2.5; 95% CI 1.3-4.4), indoor visits with people outside the household with masks (RRalways mask vs no visit=2.6; 95% CI 1.6-4.4) and without masks (RRsometimes mask vs no visit=3.5; 95% CI 2.7-5.7; RRnever mask vs no visit=5.3; 95% CI 3.1-8.9); working indoors at a place of employment with masks (RRalways mask vs no in-person=2.0, 95% CI 1.4-2.8) and without masks (RRsometimes mask vs no in-person= 2.0, 95% CI 1.1-3.5; RRnever mask vs no in-person=3.7, 95% CI 1.3-8.5); attending a salon or gym with masks (RRalways mask vs no salon/gym=1.7 (95% CI 1.1-2.4), gathering indoors and outdoors in groups of >10 (RR=1.9, 95% CI 1.2-2.0); and air travel during the pandemic (RR=1.7; 95% CI 1.1-2.6) were also associated with higher incidence rates. Among 303 seropositive individuals, 27.4% had asymptomatic infection, and 32% reported a positive SARS-CoV-2 PCR test or provider diagnosis of COVID-19. In this group, there were major gaps in the coverage of public health interventions aimed at isolation (31% isolated) and contact tracing (asked about contacts [18%]; told about exposure to a confirmed case [7.6%]). Conclusions Modifiable risk factors and low reach of public health strategies drive SARS-CoV-2 transmission across the U.S. It is critical to address inequities in incidence, reduce risk factors, and improve the reach of public health strategies in the vaccine era.

Objective To develop a causal model for the occurrence of neurocysticercosis (NC)‐related seizures and test hypotheses generated from the model. Methods We used data from a randomized controlled trial comparing albendazole with placebo among patients newly diagnosed with NC. Based on our causal model, we explored the associations among albendazole treatment, NC cyst evolution, and seizure outcomes over 24 months of follow‐up using generalized linear mixed effect models. Results We included 153 participants, of whom 51% received albendazole. The association between seizure outcomes and treatment over time demonstrated lack of linearity and heterogeneity, requiring the inclusion of time‐treatment interaction terms for valid modeling. Participants in the albendazole group had fewer seizures overall and of partial onset at all time points compared with the placebo group, but the difference increased over the first few months following treatment, then decreased over time. Generalized seizures exhibited a more complex association; those in the albendazole group had fewer seizures compared with those in the placebo group for the first few months after treatment, and then the association reversed and those in the placebo arm had fewer seizures. Adjusting for the number of NC cysts in each phase resulted in an attenuation of the strength of association between albendazole and seizure outcomes, consistent with mediation. Among participants in whom all cysts had disappeared (n = 21), none continued to have seizures. Significance Albendazole treatment is associated with a possible reduction in focal seizures in the short term (3‐6 months), perhaps by hastening the resolution of the cysts. However, the effect is not discernible over the long term, because most cysts either calcify or resolve completely, regardless of whether treated with albendazole. The stage of evolution of the cysticercus is an important consideration in the evaluation of albendazole effect on seizure outcome.

Background Passive, case-based surveillance underestimates the true extent of active infections in the population due to undiagnosed and untested cases, the exclusion of probable cases diagnosed point-of-care rapid antigen tests, and the exclusive use of at-home rapid tests which are not reported as part of case-based surveillance. The extent in which COVID-19 surveillance may be underestimating the burden of infection is likely due to time-varying factors such as decreased test-seeking behaviors and increased access to and availability of at-home testing. Objective The objective of this study is to estimate the prevalence of SARS-CoV-2 based on different definitions of a case to ascertain the extent to which cases of SARS-CoV-2 may be underestimated by case-based surveillance. Methods A survey on COVID-19 exposure, infection, and testing was administered to calculate point prevalence of SARS-CoV-2 among a diverse sample of cohort adults from February 8, 2022, to February 22, 2022. Three-point prevalence estimates were calculated among the cohort, as follows: (1) proportion positives based on polymerase chain reaction (PCR) and rapid antigen tests; (2) proportion positives based on testing exclusively with rapid at-home tests; and (3) proportion of probable undiagnosed cases. Test positivity and prevalence differences across booster status were also examined. Results Among a cohort of 4328, there were a total of 644 (14.9%) cases. The point prevalence estimate based on PCR or rapid antigen tests was 5.5% (95% CI 4.8%-6.2%), 3.7% (95% CI 3.1%-4.2%) based on at-home rapid tests, and 5.7% (95% CI 5.0%-6.4%) based on the case definition of a probable case. The total point prevalence across all definitions was 14.9% (95% CI 13.8%-16.0%). The percent positivity among PCR or rapid tests was 50.2%. No statistically significant differences were observed in prevalence between participants with a COVID-19 booster compared to fully vaccinated and nonboosted participants except among exclusive at-home rapid testers. Conclusions Our findings suggest a substantial number of cases were missed by case-based surveillance systems during the Omicron B.1.1.529 surge, when at-home testing was common. Point prevalence surveys may be a rapid tool to be used to understand SARS-CoV-2 prevalence and would be especially important during case surges to measure the scope and spread of active infections in the population.

Background Prospective cohort studies of SARS-CoV-2 incidence complement case-based surveillance and cross-sectional seroprevalence surveys. Methods We estimated the incidence of SARS-CoV-2 infection in a national cohort of 6,738 U.S. adults, enrolled March-August 2020. Using Poisson models, we examined the association of social distancing and a composite epidemiologic risk score with seroconversion. The risk score was created using LASSO regression to identify factors predictive of seroconversion. The selected factors were household crowding, confirmed case in household, indoor dining, gathering with groups ≥ 10, and no masking in gyms/salons. Results Among 4,510 individuals with ≥1 serologic test, 323 (7.3%, 95% confidence interval [CI] 6.5%-8.1%) seroconverted by January 2021. Among 3,422 participants seronegative in May-September 2020 and retested during November 2020-January 2021, 161 seroconverted over 1,646 person-years of follow-up (9.8 per 100 person-years [95%CI 8.3-11.5]). Seroincidence rate was lower among females compared to males (IRR: 0.69, 95% CI 0.50-0.94) and higher among Hispanic (IRR: 2.09, 95% CI 1.41-3.05) participants compared to White non-Hispanic. In adjusted models, participants who reported social distancing with people they did not know (IRRalways vs. never: 0.42, 95% CI 0.20-1.0) and with people they knew (IRRalways vs. never 0.64, 95%CI 0.39-1.06; IRRsometimes vs. never 0.60, 95% CI 0.38-0.96) had lower seroconversion risk. Seroconversion risk increased with epidemiologic risk score (IRRmedium vs. low 1.68, 95% CI 1.03-2.81; IRRhigh vs. low 3.49, 95% CI 2.26-5.58). Only 29% of those who seroconverted reported isolating and 19% were asked about contacts. Conclusion Modifiable risk factors and poor reach of public health strategies drove SARS-CoV-2 transmission across the U.S.

Background Vaccine hesitancy in the U.S. may limit the potential to alleviate the public health threat caused by the COVID-19 pandemic. Methods We estimated trends in and correlates of vaccine hesitancy, and its association with subsequent vaccine uptake among 5,085 United States adults from the CHASING COVID Cohort study, a national longitudinal study. Trends in willingness to vaccinate were examined longitudinally in three rounds of interviews from September to December 2020. We assessed correlates of willingness to vaccinate in December 2020. We also estimated the association between willingness to vaccinate in December 2020 and subsequent vaccine uptake in February 2021. Results Vaccine hesitancy and resistance decreased from 51% and 8% in September 2020 to 35% and 5% in December 2020, respectively. Compared to Non-Hispanic (NH) White participants, NH Black and Hispanic participants had higher adjusted odds ratios (aOR) for both vaccine hesitancy (aOR: 3.3 [95% CI: 2.6, 4.2] for NH Black and 1.8 [95% CI: 1.5, 2.2] for Hispanic) and vaccine resistance (aOR: 6.4 [95% CI: 4.3, 9.4] for NH Black and 1.9 [95% CI: 1.3, 2.7] for Hispanic). Willingness to vaccinate was associated with lower odds of vaccine uptake among 65+ year olds (aOR: 0.4, 95% CI: 0.3, 0.6 for hesitancy; aOR: 0.1, 95% CI: 0.01, 0.6 for resistance) and healthcare workers (aOR: 0.2, 95% CI: 0.1, 0.3 for hesitancy; aOR: 0.04, 95% CI: 0.006, 0.2 for resistance). Conclusions Awareness and distribution efforts should focus on vaccine hesitant vulnerable populations.

BACKGROUND Given the availability of rapid at-home tests for SARS-CoV-2, and the lack of mechanism in the United States for reporting rapid at-home results, standard surveillance underestimates the true extent of active infections in the population. OBJECTIVE The objective of this analysis was to identify the extent to which cases of SARS-CoV-2 may be underreported in standard surveillance during the recent surge of the Omicron variant. METHODS A survey on COVID-19 exposure, infection, and testing was administered to calculate point prevalence of SARS-CoV-2 among a diverse sample of cohort adults between 8-22 February 2022. Three-point prevalence estimates were calculated among the cohort 1) proportion positives based on PCR and/or rapid antigen tests, 2) proportion positive based on probable untested cases and positive cases reported from testing exclusively via rapid at-home tests, 3) a complete point prevalence estimate based on all definitions of a case. Percent positivity and prevalence differences across booster status were also examined. RESULTS Among a cohort of 4328, there were a total of 644 cases. The standard surveillance point prevalence estimate was 5.5% (95% CI: 4.8% - 6.2%). The point prevalence of probable cases and those testing positive exclusively via rapid at-home tests was 9.4% (95% CI: 8.5% - 10.3%). The complete point prevalence was 14.9% (95% CI: 13.8% - 16.0%). The percent positivity among PCR and/or rapid antigen tests was 28.1%. No statistically significant differences were observed in prevalence between participants with a COVID-19 booster compared to fully vaccinated and non-boosted participants. CONCLUSIONS Our study suggests a substantial proportion of cases were missed by standard surveillance systems during the Omicron wave, when at-home testing was common. Point prevalence surveys may be a rapid tool to be used to understand SARS-CoV-2 prevalence and would be especially important during case surges to measure the scope and spread of active infections in the population.