Biogen superspreader meeting spawned 300,000-plus U.S. coronavirus cases: study

Boston Marriott Long Wharf
A Marriott hotel in Boston was the site of an early COVID-19 superspreading event. (Marriott International)(Photo credit: Marriott International)

Even as the novel coronavirus began to spread earlier this year and news headlines raised alarms about the growing outbreak, many events still went on. In one calamitous case, Biogen's executives gathered in Boston for their annual management conference.

Shortly afterward, it was clear something had gone terribly wrong. 

In the months since, as the pandemic has gained steam around the globe, coronavirus cases associated with that meeting have mounted to hundreds of thousands, researchers estimate in a new article published in Science.

As of November 1, the researchers say, one viral variant that likely hitched a ride over from Europe with one of the meeting attendees had made its way to 245,000 people in the U.S. Another that emerged during or right after the Biogen conference reached 88,000.

In total, the researchers concluded the strains traveled across dozens of states and to several other countries.   

A Biogen spokeswoman said the pandemic has had a “very direct and personal impact on the Biogen community—as it has on many communities across the country and world." After the Biogen outbreak, many of the company's employees donated blood to a "biobank" to help researchers learn about the virus.

“As a company rooted in science, we understand the value of the data that came from the first wave of the pandemic in the Boston area, and we hope that information gleaned from these data will help continue to drive a better understanding of the transmission of this virus and efforts to address it,” she added. 

Immediately after the conference, as attendees began getting sick, public health authorities struck up an investigation and found about 100 cases directly associated with the meeting. Later, after sequencing the genomes of 28 cases, the researchers found a cluster of “highly similar viruses within a narrow time window,” indicating a superspreader event, they wrote in the Science article.

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One of the strains associated with the conference was “widely distributed” throughout Europe in January and February, and there’s “no evidence that it had entered the country independent of its appearance” at the Biogen meeting, the researchers wrote. That's the strain that hopped across the U.S. to infect around 245,000 people.

As for the second variant, the evidence shows it emerged during or possibly immediately after the conference, the researchers say, and eventually racked up around 88,000 cases. That specific variant was found in seven people who had attended the meeting, but not in any other genome databases before the event.

Together, the presence of the "two genetic signatures … with little or no evidence of transmission prior to the conference, provide markers to track the onward spread of SARS-CoV-2 from the event,” the researchers wrote. 

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The team then tracked cases in public genome databases and made estimates about the wider spread of the specific coronavirus variants.

Of course, the work has limitations. The team notes that genome samples in a public database aren't a random sample and that diagnosed cases underestimate actual transmission. Plus, there have been millions of new cases in the U.S. since the start of November, the team points out.

As of August, the researchers had concluded the conference was responsible for around 20,000 cases in the Boston area alone. And while the meeting spawned new cases in Boston and beyond, it also resulted in an uplifting story earlier in the pandemic from one attendee who said many in his community rallied around him and his family.