This stunning bit of news comes from a study by the Broad Institute of Harvard and MIT, which has not yet been peer-reviewed. The researchers collected virus samples from hospitals, nursing homes, homeless shelters, and other locations, which included nearly all confirmed cases within the first week of the epidemic in the greater Boston area. They then sequenced and analyzed 772 complete SARS-CoV-2 genomes from the area in an attempt to learn how specifically the coronavirus spreads. The research determined that the most significant superspreading event in the area was the Boston-based biotechnology company Biogen’s annual leadership meeting at the Long Wharf Marriott. The late February meeting—attended by 175 company executives—triggered an enormous spread of the virus. The researchers found one distinct strain in more than a third of the patients associated with the conference and believe it caused more than 20,000 infections in two months. The study even traced the spread of the specific strain of SARS-CoV-2 to other states and countries as far away as Singapore and Australia.

Jacob Lemieux, MD, the lead author of the study and a physician at Massachusetts General Hospital, told The New York Times that it was just a matter of bad luck that someone with the virus attended the conference—an environment conducive to its spread—and that the infected people then boarded airplanes to spread the virus further. “It’s the play of chance,” said Lemieux. “If it hadn’t been this conference, it would have been another event.” The study highlights the far-reaching effects of indoor superspreader events, how little the public knew about the virus at the time, and how it was transmitted from wealthy pharmaceutical executives to the city’s most vulnerable residents. “We’re not trying to blame,” the study’s co-author Bronwyn MacInnis, MD, director of pathogen surveillance at the Broad Institute, told The Boston Globe. “Some [viral] introductions hiss out, others light fires. The circumstances of this event—the fact that it happened so early in the epidemic and the timing of where we were with COVID in the public consciousness—meant that it had a disproportionate effect.“ae0fcc31ae342fd3a1346ebb1f342fcb RELATED: For more up-to-date information, sign up for our daily newsletter. Biogen released a statement on Aug. 25, noting how much more they now know about the coronavirus since their Boston conference, NBC10 Boston reports. “February 2020 was nearly a half year ago, and was a period when general knowledge about the coronavirus was limited,” the statement read. “We were adhering closely to the prevailing official guidelines. We never would have knowingly put anyone at risk. 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.” For more on other potential places where the contagion has gone viral, check out This Beloved Tourist Destination Has Become a COVID Superspreader.