Study: People had antibodies in five states before first coronavirus cases were confirmed

A government study released on Tuesday found that several people in five states had COVID-19 antibodies before those states confirmed their first cases of the virus last year.

The study, published as an accepted manuscript in the journal Clinical Infectious Diseases, determined that people in Illinois, Massachusetts, Wisconsin, Pennsylvania and Mississippi had COVID-19 antibodies before the states confirmed any cases.

Researchers analyzed blood samples from more than 24,000 people that were collected as part of the National Institutes of Health (NIH) All of Us study.

The blood samples, taken between Jan. 2 and March 18, 2020, underwent two COVID-19 antibody tests that identified whether certain antibodies that appear at least two weeks after infection were present. Researchers considered the samples to have antibodies if both tests returned positive results.

Results: Nine people total tested positive for antibodies, including the seven whose positive tests came before the first confirmed case in their state. Seven of the nine were from minority populations.

What it means: The presence of these antibodies in some participants suggests that they were infected with COVID-19 several weeks before their blood sample was taken.

“This study allows us to uncover more information about the beginning of the U.S. epidemic and highlights the real-world value of longitudinal research in understanding dynamics of emerging diseases like COVID-19,” Josh Denny, CEO of All of Us and an author of the study, said in a release.