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By the numbers: Majority of Mass. coronavirus cases linked to Biogen conference

Guests leaving the Marriott Long Wharf. (David L Ryan/Globe Staff )David L. Ryan/Globe Staff

A leadership meeting of the biotech firm Biogen late last month is the apparent source of the lion’s share of confirmed coronavirus infections in Massachusetts. As of Saturday afternoon, state officials said that 104 of the 138 cases in Massachusetts are related to the Biogen conference.

Here’s a look at some of the cases linked to the Cambridge-based biotech firm, followed by other details on the outbreak:

1. In Framingham, a local government spokeswoman said Sunday that a Marriott Long Wharf worker had tested positive for the disease. The Biogen conference was held at the hotel in February.


The hotel worker, who is a Framingham resident, tested positive for Covid-19 Wednesday, said Kelly McFalls, a city spokeswoman.

The positive result forced the early closing of Framingham’s Potter Road Elementary School on Wednesday at 11:30 a.m The employee’s child is enrolled as a student there, McFalls said.

2. In Cambridge, public health officials said Friday that three of the city’s residents had tested positive for the coronavirus. Cambridge officials said all three cases are connected to the Biogen conference.

One of the Cambridge residents, a person in their 50s, was a confirmed positive case, while the other two, one person in their 30s and one person in their 40s, were presumptive cases, according to the city’s public health department.

3. In Milton, two residents who tested presumptive positive for the coronavirus were linked to the conference, according to announcement by the town on Wednesday. “These individuals do not have children in the Milton Public, Private School System or day cares,’’ the Milton Health Department said in a statement.

4. In Somerville, health officials on Wednesday announced two presumptive positive cases. Both cases are linked to the Biogen conference, the city said. One of individuals is the spouse of a West Somerville Neighborhood teacher and a parent of a student at the school. The family members are quarantining at home, the city said.


5. In Arlington a woman in her 40’s who attended the Biogen conference and one of her children developed symptoms and tested positive.

6. In Boston, the Marriott Long Wharf hotel, which was the venue for the February Biogen leadership conference, said on Thursday it would close “in the interest of public health.”

7. In Norwood and Wellesley, municipal workers disinfected school buildings last weekend after cases of Covid-19 — both with ties to the Biogen conference — were reported in the communities.

In Norwood, schools Superintendent David Thomson was identified Saturday as being among 30 people who have been told they need to self-quarantine after being in close contact during a party attended by a woman who has been diagnosed with the coronavirus and who had attended the Biogen conference.

The background:

The Marriott Long Wharf was the site of a leadership conference on Feb. 26 and 27 that drew an international roster of executives from the Cambridge-based biotech firm Biogen.

The virus spread rapidly among conference attendees, but we don’t know how the virus initially got there. The conference was attended by Biogen employees from around the country and the world, but whether the initial infection was carried in from an individual or multiple people, from overseas or within the United States, has not yet been revealed.


Biogen notified the Massachusetts Department of Public Health that dozens of employees were sick on Tuesday, March 3. Federal criteria for testing appears to have loosened on Wednesday, March 4. It’s not clear why testing of meeting attendees for the coronavirus did not begin until the following Thursday, and large-scale testing was not underway until Friday.

Biogen first notified the state that some of its out-of-state employees had tested positive for Covid-19 on March 4. But when the company first learned that someone carrying the virus had been at the meeting is not clear. A Biogen spokesman declined to answer the question, saying he was unable to discuss specific cases.

If you have any information to add as we continue to report this story, please reach out.

Read the original report on how coronavirus spread at a Biogen meeting.