The results of the first statewide random sample study in the United States to measure the spread of COVID-19 indicated a general population prevalence of about 2.8 percent in Indiana.
This closely monitored study was conducted by the Indiana University Richard M. Fairbanks School of Public Health at IUPUI in collaboration with the Indiana State Department of Health. The findings were published July 21 in Morbidity and Mortality Weekly Report, the U.S. Centers for Disease Control and Prevention’s scientific publication.
Between April 25 and May 1, researchers tested more than 4,600 Hoosiers 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 from a master list of Indiana residents derived from tax returns, including filers and dependents, and an additional 900 volunteers recruited through nonrandom outreach to the African American and Hispanic communities to get a more in-depth view of the virus’s activity within hard-hit populations.
The researchers determined that 1.7 percent of participants tested positive for the novel coronavirus and an additional 1.1 percent tested positive for antibodies, resulting in an estimated overall population prevalence of SARS-CoV-2 of 2.8 percent. According to the department of health, An estimated 187,802 Hoosiers were infected with COVID-19 at the time of the study, approximately 10 times higher than the confirmed cases in the state.
Participants who reported living with someone who tested positive for COVID-19 had a prevalence rate of 33.6 percent.
The research team also found that 44.2 percent of participants who tested positive reported no symptoms during the two weeks before testing. Of those who tested positive, 60.3 percent of males reported being asymptomatic, compared to 24.5 of females who were asymptomatic.
Rates of current or previous infection were significantly higher among Hispanic participants, at 8.32 percent, than among non-Hispanics, at 2.29 percent.
The nonrandom sample had higher infection rates, including 22.8 percent of participants who were currently infected; 20 percent of those infected reported being asymptomatic. These findings suggest that nonrandom samples are more suitable for determining the impact of the virus in vulnerable communities, but not for deriving state estimates of infections.