Stanford researchers are testing around 10,000 Major League Baseball (MLB) employees for COVID-19 antibodies in a study co-led by the University of Southern California and the Sports Medicine Research and Testing Laboratory (SMRTL). The MLB’s efficient cooperation and national scope makes it a good organization to use for a study sample, researchers said.

The MLB study will add to a growing body of antibody research that may help scientists estimate how much of the population has already been exposed to COVID-19. Stanford researchers expressed hope that the MLB will provide useful data quickly.

“They have a fantastic organization with the ability to very rapidly deploy a study of this size,” said Stanford medical school professor Jayanta Bhattacharya M.D. ’97 Ph.D. ’00, who is analyzing the study data. “Otherwise it would have taken years to organize.”

At least 27 out of 30 MLB teams are taking part in the research, Bhattacharya said. But only a fraction of the study participants are athletes — the rest include concession stand workers, security personnel, office staff, coaches, trainers and medical staff. 

Employees took the tests at home using a device that looks “like a pregnancy test,” Bhattacharya said, and researchers are currently analyzing their findings.

Stephen Piscotty ’14, an outfielder for the Oakland A’s, took an antibody test a week and a half ago as part of the Stanford study.

“It was really pretty simple,” Piscotty said. “You prick your finger with a little needle that they give you. All you need is a drop or two of blood.”

Piscotty and his wife, who also participated in the study, both tested negative for antibodies, indicating it is unlikely that they have been exposed to COVID-19. The results appeared within 10 minutes, then they both photographed their tests and emailed them back to the researchers.

“I wanted to help in some way,” Piscotty said.

Bhattacharya said the MLB makes a good study sample for multiple reasons, including the organization’s efficiency and willingness to participate, the employees’ regular interactions with the public and their geographic diversity.

“It’s an organization of nationwide scope, and we don’t have a nationwide study yet,” Bhattacharya said. “Of course, this won’t be nationally representative in the sense of representation of the national population, but it is a study all across the nation because the MLB teams are located all across the nation.”

Bhattacharya and other researchers are working on a paper that will include the results of the MLB study and which they hope will be available soon.

“We have to do a lot of double-checking,” he said.

A mid-April antibody study of Santa Clara County led by Bhattacharya and other Stanford researchers attracted controversy when scientists took to the internet to question its methods. The Santa Clara study made national news for indicating that rates of exposure to COVID-19 were 50 to 85 times higher than previously assumed.

Antibody research has also sparked debate in recent weeks as some commentators have suggested it will allow Americans to return to work faster. Others say that the existing tests are not reliable enough for that purpose. The World Health Organization (WHO) this week warned against the idea of issuing “immunity passports” that would allow people who have recovered from COVID-19 or who have tested positive for antibodies to resume normal activities.

“I think we have to be very cautious about extrapolating antibody results to single individuals,” said Stanford medical school professor John Ioannidis, who is working on COVID-19 antibody research but is not involved in the MLB study. “I think the passport idea is not a good idea based on what we know.”

“No single study will give you the full truth,” Ioannidis added. “This is why we perform multiple studies. Each one of them is giving some complementary insights.”

Bhattacharya said the MLB study will not prove whether a person who tests positive for antibodies is immune to infection from COVID-19.

“What this test does is, it tells you that antibodies are present that are specific to COVID-19,” he said. “That just tells you you had a previous infection. It doesn’t tell you that you are immune from another infection from COVID-19. It might, but we don’t know yet.”

Contact Jasmine Kerber at jkerber ‘at’ stanford.edu.