According to a Boston Globe report, the international company meeting at the Marriott Long Wharf hotel in Boston was said to have resulted in 99 identified cases of the virus, but, according to scientists studying early cases, that number reached roughly 20,000 by early May in those four counties.
Researchers studied all confirmed early cases of COVID-19 in the area by changes in the genetic makeup of coronaviruses to gauge the spread of the event hosted by Cambridge, Mass.-based Biogen, according to The Globe.
Almost all of the 772 cases observed came from Essex, Middlesex, Norfolk and Suffolk counties. Through observing mutations in the genetic code of the viruses, the researchers identified more than 80 distinct SARS-CoV-2 genomes that spread around the Boston area, the report says.
The researchers found that 289 of the 772 cases had one unique genetic signature traceable to the meeting Biogen held on Feb. 26 and Feb. 27. Of those 289 cases, the study says 122 were people living in Boston-area homeless shelters and employees who work at those shelters.
The report states that the study has not yet been peer-reviewed for publication, but the researchers claim that their estimate was garnered based on viruses isolated from 772 local patients.
Harvard T.H. Chan School of Public Health professor of epidemiology Caroline Buckee, who was not among the study’s researchers, told the newspaper that she found the estimate from the study to be believable.
“Super-spreading is really a key component of how we ended up with an epidemic of this gravity,” Buckee told The Globe. “If you think about it, all the cases in the whole world originated from one case. That’s the nature of the exponential growth of epidemics.”
When the Biogen conference took place, the understanding of the virus was far more limited than it is today, as a number of safety measures have been put in place across the globe in an effort to combat the virus, which has led to more than 176,000 deaths in the U.S. so far. However, in a statement to The Globe, Biogen did not dispute the study or the researchers’ estimates.
“We never would have knowingly put anyone at risk,” Biogen told The Globe. “When we learned a number of our colleagues were ill, we did not know the cause was COVID-19, but we immediately notified public health authorities and took steps to limit the spread.”