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BackgroundDuring a pandemic, estimates of geographic variability in disease burden are important but limited by the availability and quality of data. MethodsWe propose a framework for estimating geographic variability in testing effort, total number of infections, and infection fatality ratio (IFR). Because symptomatic people are more likely to seek testing, we use a noncentral hypergeometric model that accounts for differential probability of positive tests. We apply this framework to the United States (U.S.) COVID-19 pandemic to estimate county-level SARS-CoV-2 IFRs from March 1, 2020 to October 31, 2020. Using data on population size, number of observed cases, number of reported deaths in each U.S. county and state, and number of tests in each U.S. state, we develop a series of estimators to identify the number of SARS-CoV-2 infections and IFRs at the county level. We then perform a simulation and compare the estimated values to simulated values to demonstrate the validity of our approach. FindingsApplying the county-level estimators to the real, unsimulated COVID-19 data spanning March 1, 2020 to October 31, 2020 from across the U.S., we found that IFRs varied from 0 to 0.0273, with an interquartile range of 0.0022 and a median of 0.0018. The estimators for IFRs, number of infections, and number of tests showed high accuracy and precision; for instance, when applied to simulated validation data sets, across counties, Pearson correlation coefficients between estimator means and true values were 0.88, 0.95, and 0.74, respectively. InterpretationWe propose an estimation framework that can be used to identify area-level variation in IFRs and performs well to estimate county-level IFRs in the U.S. COVID-19 pandemic.
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ImportanceEssential workers in agriculture and food production have been severely affected by the ongoing COVID-19 pandemic. ObjectiveTo identify risk factors associated with SARS-CoV-2 shedding and antibody response in farmworkers in California. DesignThis cross-sectional study collected survey data and determined current SARS-CoV-2 shedding and seropositivity among 1,107 farmworkers in Californias Salinas Valley from 16 July to 30 November 2020. SettingFarmworkers receiving transcription-mediated amplification (TMA) tests for SARS-CoV-2 infection at federally qualified community clinics and community sites were invited to participate in our study. ParticipantsIndividuals were eligible if they were not pregnant, [≥]18 years old, had conducted farm work since the pandemic started, and were proficient in English or Spanish. ExposuresSociodemographic, household, community, and workplace characteristics. Main Outcome(s) and Measure(s)Current (as indicated by TMA positivity) and historical (as indicated by IgG seropositivity) SARS-CoV-2 infection. ResultsMost farmworkers enrolled in the study were born in Mexico, had primary school or lower levels of educational attainment, and were overweight or obese. Current SARS-CoV-2 shedding was associated in multivariable analyses with attained only primary or lower educational levels (RR=1.32; 95% CI: 0.99-1.76), speaking an indigenous language at home (RR=1.30; 0.97-1.73), working in the fields (RR=1.60; 1.03-2.50), and exposure to known or suspected COVID-19 case at home (RR=2.98; 2.06-4.32) or in the workplace (RR=1.59; 1.18-2.14). Antibody detection was associated with residential exposures including living in crowded housing (RR=1.23; 0.98-1.53), with children (RR=1.40; 1.1-1.76) or unrelated roommates (RR=1.40; 1.19-1.64), and with a known or suspected COVID-19 case (RR=1.59; 1.13-2.24). Those who were obese (RR=1.65; 1.01-2.70) or diabetic (RR=1.31; 0.98-1.75) were also more likely to be seropositive. Farmworkers who lived in rural areas other than Greenfield (RR=0.58; 0.47-0.71), worked indoors (RR=0.68; 0.61-0.77), or whose employer provided them with information on how to protect themselves at work (RR=0.59; 0.40-0.86) had lower risk of prior infection. Conclusions and RelevanceOur findings suggest both residential and workplace exposures are contributing to SARS-CoV-2 infection among farmworkers in California. Urgent distribution of COVID-19 vaccines is warranted given this populations increased risk of infection and the essential nature of their work.
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As essential personnel, United States farmworkers have continued working in-person throughout the COVID-19 pandemic. We undertook prospective surveillance of SARS-CoV-2 infection and antibody prevalence among farmworkers in Californias Salinas Valley from 15 June to 30 November, 2020. Over this period, we observed 22.1% (1514/6864) positivity for current SARS-CoV-2 by nucleic acid detection among farmworkers tested at federally-qualified migrant and community health clinics, as compared to 17.2% (1255/7305) among other adults from the same communities (risk ratio, 1.29; 95% confidence interval, 1.20-1.37). In a nested study enrolling 1,115 farmworkers, prevalence of current infection was 27.7% among farmworkers reporting [≥]1 potential COVID-19 symptom, and 7.2% among farmworkers without symptoms (adjusted odds ratio 4.17; 2.86-6.09). Prevalence of anti-SARS-CoV-2 IgG antibodies increased from 10.5% (6.0-18.4%) between 16 July-31 August to 21.2% (16.6-27.4%) between 1-30 November. The high observed prevalence of infection among farmworkers underscores the need for vaccination and other preventive interventions.
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ObjectivesTo examine the impact of the COVID-19 pandemic on farmworkers from Monterey County, California. MethodsWe recruited adult farmworkers (n=1115) between July 16, 2020 and November 30, 2020. We collected information on sociodemographic characteristics, health behaviors, economic and social stressors experienced during COVID-19, and willingness to be vaccinated via interviews by phone. ResultsStudy participants, particularly female farmworkers, reported adverse effects of the pandemic on their mental health and home environment (e.g., 24% overall reported depression and/or anxiety symptoms). The pandemic also resulted in greater financial burden for many farmworkers, with 37% food insecure and 51% unable to pay bills. Half of respondents reported that they were extremely likely to be vaccinated. Vaccine hesitancy was most common in participants who were women, younger, born in the United States, and living in more rural areas. ConclusionsWe found that the pandemic has substantially impacted the mental and physical health and economic and food security of farmworkers. Public Health ImplicationsThis study highlights the need to provide farmworkers with supplemental income, and increased mental and family health, and food support services.