The number of participants included in the Stanford University study. Los Altos, where Ardis G. Egan Junior High School is located, is in the shaded area south of Palo Alto.

The journalists at BuzzFeed News are proud to bring you trustworthy and relevant reporting about the coronavirus. To help keep this news free, become a member and sign up for our newsletter, Outbreak Today .

A Stanford University professor’s wife invited parents in a wealthy enclave of Northern California to sign up for her husband’s coronavirus antibody study this month, falsely claiming that an “FDA approved” test would tell them if they had immunity and could “return to work without fear,” according to an email obtained by BuzzFeed News.

The email, sent to a listserv for Ardis G. Egan Junior High School in the city of Los Altos on Thursday, April 2, advertised a study set to begin the next day. With the subject line “COVID-19 antibody testing - FREE,” the email described how participants could gain “peace of mind” and “know if you are immune.” The results would help researchers calculate the virus’s spread throughout the surrounding county of Santa Clara, according to the message sent by Catherine Su, a radiation oncologist married to Jay Bhattacharya, the Stanford professor of medicine leading the study.

Weeks later, early results from Bhattacharya’s team would conclude that, based on the tests, the area had 50 to 85 times more infections than reported cases. That finding, along with their claim that the coronavirus would therefore have a lower fatality rate than previously thought, made national headlines. But almost as immediately, the study came under fire from scientists, who said it was based on a heavily flawed data analysis that ignored questions about the antibody test’s false positive rate — as well as a problematic Facebook recruitment strategy.

The email reveals that the researchers did not disclose another way participants were recruited that could have further skewed the results. In addition to targeting a specific demographic of parents in a wealthy part of Silicon Valley — making it even less likely that the participants represented a random sample — the email falsely claimed that the study’s antibody test was FDA approved, and was worded in a way that might have disproportionately attracted people who had previously been sick. It also misrepresented what participants could learn about their health from the testing.

Given how new this coronavirus is, scientists do not definitively know how long antibodies can protect you from getting sick again. Yet Su’s email stated: “If you have antibodies against the virus, you are FREE from the danger of a) getting sick or b) spreading the virus. In China and U.K. they are asking for proof of immunity before returning to work. If you know any small business owners or employees that have been laid off, let them know -- they no longer need to quarantine and can return to work without fear.”

Marm Kilpatrick, an infectious disease researcher at the University of California at Santa Cruz, told BuzzFeed News these statements were “super concerning.”

“They're offering people information about their possible immunity that I don’t think they can accurately give them, that might put these people in danger if they take actions like interact with people without social distancing in unsafe ways,” he said.

Asked for comment, Bhattacharya said that his wife’s email was not associated with the research team’s work. “The email you reference was sent out without my permission or my knowledge or the permission of the research team,” he wrote in an email to BuzzFeed News. He said that he believes the note was also shared on social media sites.

Bhattacharya acknowledged that the email skewed the makeup of the study’s participants, but argued that the researchers corrected for the difference in volunteers. “Our tracking of signups very strongly suggests that this email attracted many people from the wealthier and healthier parts of Santa Clara County to seek to volunteer for the study,” he wrote. “In real time, we took immediate steps to slow the recruitment from these areas and open up recruitment from all around Santa Clara County.”

He added that a revised preprint would be released in the next two days and would address criticisms of the study’s sample selection.

Su did not return requests for comment.

On Monday, Stanford spokesperson Julie Greicius said in a statement, “Stanford Medicine is aware of news reports regarding the recruitment of participants for the recent COVID-19 seroprevalence study in Santa Clara County. These matters are being handled by the appropriate committees at Stanford.”