An antibody study carried out in Indiana concluded that, as of May 1, 2.8 percent of the state’s residents had been infected with the coronavirus.
As part of the first phase of the study, a collaboration between the Indiana State Department of Health and the Fairbanks School, researchers tested more than 4,600 Hoosiers between April 25 and May 1 for viral infections and antibodies of SARS-CoV-2, the novel coronavirus that causes COVID-19. This number includes more than 3,600 people who were randomly selected and an additional 900 volunteers recruited through outreach to the African American and Hispanic communities to more accurately represent state demographics.
After analyzing these test results, IUPUI public health researchers determined that during the last week of April, 1.7 percent of participants tested positive for the novel coronavirus and an additional 1.1 percent tested positive for antibodies — bringing the estimated population prevalence of the virus in the state to 2.8 percent, or approximately 186,000 Hoosiers who were actively or previously infected as of May 1, Menachemi said.
As of the same date, the state’s testing showed about 17,000 cumulative cases — not including deaths — suggesting that only about one out of every 11 true infections were identified by tests focused on symptomatic or high-risk people.
As we’ve all learned by now, once you have a more accurate sense of the percentage of the population that has been infected you can combine that with the death rate and estimate the infection fatality rate, i.e. how deadly is the virus.