One event sent virus around the globe
None of the biotech executives at the meeting noticed the uninvited guest.
They had flown to Boston from across the globe for a meeting of the drug company Biogen, and were busy catching up with colleagues and hobnobbing with management.
For two days they shook hands, kissed cheeks, passed each other the salad tongs at the hotel buffet, never realizing that one among them carried the coronavirus in their lungs.
By the meeting’s end on Feb. 27, the infection had infiltrated many more people: a research director, a photographer, the general manager for the company’s east division. They took the virus home with them to the Boston suburbs, Indiana and North Carolina, to Slovakia, Australia and Singapore.
Over the following two weeks, the virus that circulated among conference attendees was implicated in at least 35 new cases. In April, the same distinctive viral substrain swirled through two Boston homeless shelters, where it infected 122 residents.
Scientists know all this thanks to a mistake made during the coronavirus’ replication process — a simple switch of two letters in the virus’s 30,000-character genetic code.
This mutation appeared in two patients in France at almost exactly the same time genetically matching viruses were sickening dozens of people at the Biogen meeting. After the conference, the mutation spread along with the infection.
Now, a sweeping study of nearly 800 coronavirus genomes has found that viruses carrying the conference’s characteristic mutation infected hundreds of people in the Boston area, as well as victims from Alaska to Senegal to Luxembourg.
As of mid-July, the variant had been found in about one-third of the cases sequenced in Massachusetts and 3 percent of all genomes studied in the United States.
The study, which was added Tuesday to the preprint website MedRxiv, is likely the largest genomic analysis of any U.S. outbreak so far and is among the most detailed looks at how coronavirus cases exploded in the pandemic’s first wave.
It documents the cost of the world’s naivete this spring, when people traveling for events such as the Biogen conference unwittingly imported the virus into Massachusetts dozens of times.
It reveals the connections between seemingly disparate communities, showing how an outbreak at a gathering of wealthy executives was only a few infections removed from sickening some of Boston’s most vulnerable residents.
And it highlights the outsize role of indoor “superspreading events” in accelerating and sustaining transmission. With genetic data, said coauthor Bronwyn MacInnis, “a record of our poor decisions is being captured in a whole new way.”