Major League Baseball employees, from players to stadium workers to executives, are participating this week in a 10,000-person study aimed at understanding how many people in various parts of the United States have been infected with the coronavirus.

Each participant will have a finger pricked to produce blood that will be tested for the presence of antibodies, which indicates a past infection even in people who have never displayed symptoms of COVID-19, the disease caused by the coronavirus. The test for the virus itself can reveal only a current infection.

One of the biggest hurdles in determining when to reopen parts of the United States is the uncertainty about the number of people who have been infected overall and who, as a result, may now have some sort of immunity.

Teams of researchers from Stanford University, the University of Southern California and a prominent anti-doping lab in Salt Lake City are collaborating on the study involving MLB. They believe it is the first and most extensive research of its kind in the United States.

“This kind of study would have taken years to organize outside of this setting,” said Dr. Jay Bhattacharya, a professor of medicine at Stanford who is leading the study. “With the help of MLB, we’ve managed to do this in a matter of weeks.”

As the coronavirus pandemic spread and sidelined sport after sport, Daniel Eichner, the executive director of the Sports Medicine Research and Testing Laboratory in Salt Lake City, realized that his facility would have few, if any, anti-doping responsibilities for quite a while.


So, Eichner said, his laboratory redirected its focus and ordered large quantities of antibody tests that had been used successfully in some Asian countries.

To carry out representative testing, the researchers needed a large group of people who were spread all over the country. Bhattacharya said that he had reached out to an array of corporations and that MLB, which already had a relationship with Eichner, was the quickest to agree. The major leagues, in response to the pandemic, shut down spring training March 12 and has no specific plans to resume play.

“There’s nothing in it for the teams or MLB on this one,” Eichner said. “This is purely to drive public health policy.”

Bhattacharya said MLB’s pool of employees offered “a big swath of the American population.” He added that nearly all of MLB’s 30 teams were participating and that it was up to each team to distribute the tests.

Because many MLB employees and players live in areas with shelter-in-place rules in effect, many kits have been mailed to participants. The test can produce results in 15 minutes, Bhattacharya said, and photographs documenting the results can be submitted electronically to the researchers.

A spokesman for the baseball players union said the study was “voluntary, strictly part of independent research aimed at gathering data — it’s not connected to resumption of play — and players’ identities will be separated from the data.”


In addition to studying the MLB populations, the researchers are using the tests Eichner provided to conduct antibody screening in Los Angeles and in Santa Clara County, California.

Bhattacharya said he hoped to analyze the data from MLB’s employees and players and write a paper as soon as possible, to help guide the easing of stay-at-home restrictions.

“I’d love to be able to go to Fenway Park someday again,” he said. “But that’s not really the main purpose. The main purpose is so that we can inform nationwide policy in every community about how far along we are in this epidemic and if it is safe enough to open up the economy.”