That figure is nearly 10 times higher than the reported number of confirmed cases in the state as of April 29, which was 17,800, CDC researchers said.
The findings are the latest to suggest that actual infections of the new coronavirus exceed reported case totals, they said.
"The finding[s] suggest that Indiana was in the early stage of the pandemic when the study was conducted," the researchers wrote.
Officials in Indiana issued a mask mandate this week as part of an effort to contain the outbreak.
The estimates are based on blood tests for COVID-19 antibodies performed on nearly 3,700 infected patients in Indiana, conducted between April 25 and 29, the researchers said.
If accurate, the analysis indicates that just under 3% of the state's 6.73 million people were infected with the virus at that time, according to the researchers.
As many as 44% of those infected had no obvious symptoms of the virus, which might be why many cases weren't reported to state health officials, the agency said.
Despite the higher rate of infections suggested by the findings, the majority of the state's population remains "susceptible" to the virus, researchers said.
"Adherence to evidence-based public health mitigation and containment measures -- social distancing, consistent and correct use of face coverings and hand hygiene -- is needed to reduce [a] surge in hospitalizations," they wrote.
Similarly, an analysis of COVID-19 antibody testing in DeKalb and Fulton counties in Georgia -- including the Atlanta metropolitan area -- performed between April 28 and May 3 indicates as many as 2.5% of the people in the region had been infected, CDC researchers said.
Nearly half of those with antibodies against the virus -- which suggests they had been infected -- were Black, the CDC said. About 30% of Georgia's population is Black, according to U.S. Census figures.