Jay Bhattacharya has been studying results of COVID-19 blood tests of thousands of employees of Major League Baseball. Preliminary results indicate that just 0.7% of the employees from the MLB’s 30 teams were positive for COVID-19 antibodies — lower than the results from earlier studies.

The MLB study, conducted in collaboration with researchers from the University of Southern California and the Sports Medicine Research and Testing Laboratory in Salt Lake City, is the largest seroprevalence study of COVID-19, and the first on a national scale.

“I was expecting a little bit of a larger number,” Bhattacharya told reporters in an April 10 conference call. “It shows the value of doing the science as opposed to guessing.”

Test kits, distributed by a third party, were sent to some 10,000 MLB employees; 5,754 of them responded, using a pin prick to draw blood. Bhattacharya said that about 70% of those who tested positive for the COVID-19 antibodies were asymptomatic.

The study will be published on a preprint server later this week and will also be submitted to a national medical journal for where it will undergo peer review.

“This is a special population. It’s not representative of the American population at large,” Bhattacharya said. “But it’s an important population because it allows us to get a peek at the nationwide prevalence.”

The study has led to many media reports, including the ones below.