Putting the super in superspreader: Researchers say Covid-19 from that Biogen conference led to widespread infection among Boston homeless, spread around the world

An analysis of the genetic makeup of Covid-19 samples from the early days of the pandemic in Massachusetts suggests a two-day conference at the Marriott Long Wharf provided the spark that set off a Covid-19 conflagration in a state not yet fully prepared to deal with it.

The paper, by researchers associated with Cambridge's Broad Institute, Harvard and Massachusetts General, shows that managers from biotech company Biogen's global offices quickly contracted and began to spread a particular variant of the virus during a conference at the waterside hotel on Feb. 26 and 27 - a strain that had been circulating only in Europe in February, before some managers from Europe came to the Marriott Long Wharf not knowing they had it.

Analysis of samples collected during "universal" testing that started at the Pine Street Inn just two weeks later showed a high percentage of the same variant, the researchers write.

Participants in the meeting eventually spread the Covid-19 strain to several cities in the US and abroad, the researchers write.

The researchers write that, at first, cases in Massachusetts were largely imported from elsewhere - such as the state's first three known cases, a UMass Boston student who returned from Wuhan and somebody who went on a school trip to Italy.

Those first three cases did not result in any spread; all were put into quarantine for two weeks. The genetics show as many as 80 "introductions" from outside the state, at first from other continents, then, as international travel was halted, from the rest of the US.

But by April, it was too late for further "containment" in Massachusetts - by then, there was enough of the virus around here that after April 1, most new Massachusetts cases were the result of people getting it from other people in the state. The strain from the conference, they write, was "a major contributor to sustained community transmission."

Among the places it spread locally: Norwood, where just a couple of days after the Biogent meeting, a number of town officials and workers had to go into quarantine after learning they'd attended a local party on March 1 with a Biogen participant who tested positive. Among them: The town administrator, who himself tested positive a few days later.