The study, a collaborative effort between Deaconess Health System and the Indiana University School of Medicine-Evansville, was the first local study on COVID-19 prevalence in our community.
“Having this data is invaluable for local decision making,” said Evansville Mayor Lloyd Winnecke. “These results also suggest that local residents’ efforts at social distancing and other precautionary measures have helped keep our area’s numbers lower, which I am very pleased to see.”
During the week ending May 8, more than 800 local employees were tested in a statistical representation of the overall workforce. The study sampling indicated that 0.67 percent had active COVID-19 infection, and 1.3 percent had SARS-CoV-2 antibodies, which indicates prior infection.
Adjusting for the study’s sampling model, the total positivity rate is 1.9 percent, meaning that just under 2 percent of the local workforce has contracted the SARS-CoV-2 virus. This rate is 32 percent less than the overall state population prevalence of 2.8 percent, as indicated by the recent statewide study by IU and the Indiana State Department of Health*.
This local study differs from the statewide study, as this local study was workforce-focused, took place over a very short time span (giving a precise snapshot of actual prevalence), and was also a larger representative sample of our region.
On May 8, the same date the testing ended, the Vanderburgh County Health Department showed about 175 cumulative cases. Because testing to this point has only been focused on symptomatic or high-risk people (per CDC guidelines), the prevalence of 1.9% compared to the local population suggests that locally only about one out of every 20 true infections have been identified by testing, to date.
The various employers in the testing group represented manufacturing, healthcare, financial services, on-site service industry and office settings.
“Our study and testing of employees from six different area employers—incorporating several different workforces and work settings-- has given us a statistically significant representation of the overall local workforce population,” said Dr. Koleilat. “The results give valuable insights regarding how employers of various types can resume operations while protecting employees.”
All reported results are aggregated (combined); individual employers received results for their specific workplaces, with participant information de-identified. Those who had employees with positive test results were contacted by the employees’ respective home county health departments for any appropriate contact tracing and notifications.
Study participants who reported known contact with someone with suspected or confirmed COVID-19 (often within their own households) were five times more likely to test positive themselves. Coupled with the 1.9% general prevalence, this information indicates that a large number of local infections have been contained to households or close contacts.
“We are glad to see these lower numbers for our region, and I applaud our community for helping to keep our numbers down,” said Dr. James Porter, President, Deaconess Health System. “Slowing the spread of the virus has given hospitals [such as Deaconess] time to create the processes and protocols to provide safe care for all of our patients, and to implement the needed steps to protect frontline healthcare workers.”
“While the results are good news for the community and local employers, I want to stress that this study shows us that about 98% of people in the area haven’t been infected and are still at risk for this virus,” said Dr. Koleilat. “As we reopen more aspects our economy, ongoing social distancing, hygiene and widespread mask usage will help protect those who are at highest risk of infection.”
Statistical selection of participants and analysis of results were conducted by faculty from IU School of Medicine-Evansville, supported by the Indiana Clinical and Translational Sciences Institute, as well as the Department of Biostatistics and Richard M. Fairbanks School of Public Health at Indiana University.