Courtesy of Ohio Department of Health
Summary:
For 20 days in July 2020, we measured the prevalence of current and past COVID-19 test results in a representative sample of 727 Ohio adults. Participants provided a nasopharyngeal swab for PCR detection of a current onset of COVID-19, and a blood sample for detection of antibodies indicative of past COVID-19. Using a Bayesian Latent Class Model with multilevel regression and poststratification, the statewide prevalence of current COVID-19 was 0.9% (95% credible interval, 0.1% to 2.0%). The statewide prevalence of past COVID-19 was 1.5% (95% credible interval, 0.3% to 2.9%). While hundreds of thousands of Ohio adults have had COVID-19 since March 2020, community spread is still ongoing and millions remain susceptible.
Prevalence of COVID-19:
Nearly all (n=716, 98%) participants had valid nasopharyngeal swab PCR test results. From the Bayesian Latent Class Model with multilevel regression and poststratification, the statewide prevalence of current COVID-19 was 0.9% (95% credible interval, 0.1% to 2.0%). Given the size of the adult population of Ohio, this prevalence corresponds to approximately 80,000 COVID-19 cases among Ohio adults during that time period. Meanwhile, approximately 23,000 Ohio adults were diagnosed with COVID-19 during the same 20 days, suggesting that the total cases in the state were approximately 3.5 times as high as diagnosed cases. A smaller proportion (n=592, 81%) of participants had valid antibody results for all three assays. Again using a Bayesian Latent Class Model, the statewide prevalence of past COVID-19 was 1.5% (95% credible interval, 0.3% to 2.9%), corresponding to approximately 133,000 Ohio adults with evidence of past COVID-19. It is important to note that the antibodies measured in this analysis remain detectable for an uncertain period of time; current data suggest that most people will no longer have detectable antibodies three months after infection.
