WASHINGTON — When it was disclosed last spring that the coronavirus had stealthily infected 99 people after the Cambridge, Massachusetts, pharmaceutical company Biogen held a two-day conference in February, it helped add the term “superspreader” to the pandemic lexicon.
“It’s a cautionary tale,” said Bronwyn MacInnis, a genomic epidemiologist at the Broad Institute of Harvard and MIT. “When we hear these stories of clusters where 20 or 50 or 100 were affected, that does not account for what happens after.”The analysis, by more than 50 health care experts and researchers based primarily in the Boston area, was published Thursday in Science, the journal of the American Association for the Advancement of Science.
The analysis of 28 cases determined that each person had been infected with a strain of the coronavirus, named C2416T, that had not previously been seen in the United States. The only known instances of the strain that preceded the Biogen conference involved two French patients, ages 87 and 88. By May, it was estimated that between 44,000 and 56,000 known coronavirus cases were directly tied to the Biogen conference. About 40% were in Boston, but the C2416T strain was carried across the country, to Indiana, Florida, North Carolina and perhaps elsewhere by people who had been at the meeting.
One of the study’s more arresting findings was that within a month of the Biogen conference, the virus strain introduced there had made its way to Boston-area homeless shelters. Tests at the shelters, affiliated with the Boston Health Care for the Homeless Program, found 14 strains of the coronavirus, four of which appeared to have become superspreaders. The researchers found that two clusters of cases that resembled superspreader events were associated with the virus from the conference.