Three employees of biotech giant Biogen tested positive for the new coronavirus after attending a management meeting with about 175 co-workers over two days last week at a Boston hotel, the company said Thursday.

None of the three infected employees lives in Massachusetts, but the location, size, and duration of the gathering raised concerns about a wider outbreak of the infection in the state. Officials at the Marriott Long Wharf Hotel, where the Biogen event was held, didn’t return a phone call seeking comment.

On Wednesday Biogen sent an e-mail telling all employees who attended the management meeting to work from home until March 16, regardless of whether they had symptoms, according to David Caouette, a spokesman for the Cambridge-based company.

Before Biogen disclosed the infections, Massachusetts had three cases of Covid-19, the illness caused by the virus — one confirmed and two presumptive, according to the state Department of Public Health.

The second presumptive case was announced Thursday, a Middlesex County woman in her 60s who recently traveled to Europe, including northern Italy. She was symptomatic but did not require hospitalization and is recovering at home, health department officials said.

Public Health Commissioner Monica Bharel urged Massachusetts residents to follow the guidelines of the Centers for Disease Control and Prevention for dealing with the disease.

“While the risk to Massachusetts remains low, residents should make sure they and their families are well-informed about Covid-19 and heed the CDC’s updated international travel health alert,” she said.

As of Thursday evening, there were 230 confirmed coronavirus cases in the United States and 14 deaths — 13 in the Seattle area and one in California, according to a database run by Johns Hopkins University using official reports from around the world. There were more than 98,000 cases globally, with nearly 3,350 deaths.

Earlier on Thursday, officials in Tennessee confirmed the state’s first Covid-19 case, a man who had recently returned from traveling to Boston. He has a mild illness and is isolated at his home in Williamson County.

Governor Charlie Baker said Thursday night that he was “under the impression at this point in time” that the Tennessee patient is one of the infected Biogen employees.

“We’ve been talking to the city’s department of public health and to the folks at Biogen and to others about that particular situation,” Baker said at the Old South Meeting House, where he spoke at a ceremony marking the anniversary of the Boston Massacre. "And obviously we’re going to work through the details on that over the next day or two.”

The other two Biogen employees reside in Europe, the company said.

Caouette, the Biogen spokesman, declined to say when Biogen became aware of the infections or provide other specifics. Several other attendees of the management meeting on Feb. 26 and 27 had flu-like symptoms afterward.

The company has also contacted officials at the hotel that hosted the meeting, Caouette said.

All of “these individuals are doing well, improving and under the care of their healthcare providers,” the company said in a statement.

“Protecting our employees and our communities is our priority,” said Biogen, which has 2,400 workers in Massachusetts and 7,500 worldwide. “Biogen has been in regular contact with the relevant public health officials since the time the first cases of illness were reported.”

Since January, Massachusetts has tested 25 residents for the coronavirus, including the three identified by the health department as having the disease, according to the state. As of Wednesday, 719 people have been subject to self quarantine; about 249 are still currently quarantined, state officials said.

Citing advice from the state, MIT said Thursday that it had suspended all international school-related travel for faculty, students, and staff.

“Rare exceptions will be considered,” president Rafael Reif said in an e-mail to the MIT community. He also said MIT was discouraging personal international travel.

Baker said that the coronavirus situation in Massachusetts is evolving but “still relatively low risk,” and he encouraged residents to wash their hands and be hygienic and to stay home if they get sick.

At the Old South Meeting House, Baker said Massport is taking additional precautions at Logan Airport based on guidance from the CDC. He added that domestic travel, based on current guidance from the federal government, “is perfectly appropriate.”

Correction: An earlier version of this story misstated the number of Covid-19 deaths in the Seattle area. Thirteen people have died there.

Jaclyn Reiss, Nestor Ramos, and Hanna Krueger of the Globe staff contributed to this report.

Biogen’s CEO, chief financial officer, and head of research and development were among those at a corporate meeting last week attended by eight people who later tested positive for the novel coronavirus, and the company said it has taken aggressive steps to prevent other employees from falling ill.

The executives — Michel Vounatsos, Jeff Capello, and Alfred Sandrock — attended the annual meeting, according to people familiar with the matter. Biogen on Friday confirmed their attendance at the meeting.

The company said the individuals known to have COVID-19, the disease caused by the coronavirus, are currently “doing well, improving and under the care of their healthcare providers.” It added, “Protecting our employees and our communities is our priority.”

All of the approximately 175 meeting attendees, with or without flu-like symptoms, have been directed to work from home for two weeks. The company said it was asking all “office-based Biogen employees and contractors” in Massachusetts, Research Triangle Park, N.C., and Baar, Switzerland, to work from home until further notice, and “restricting travel” through the end of the month.

In a statement Friday night, Biogen said meeting attendees who are symptomatic would be contacted by public health authorities to be tested, if they haven’t already, and “must quarantine themselves.” They also have been asked to stay isolated from family members or others they live with, “and these close contacts must also be quarantined until further notice,” the statement said.

Attendees without symptoms also have been asked to quarantine themselves until further notice and have the people they live with work from home.

“We recognize that this is a difficult situation for our colleagues and their loved ones,” the statement said.

Biogen, based in Cambridge, Mass., is one of the first biotechnology companies ever founded. It has about 7,800 employees and annual sales of $14 billion, thanks to treatments for multiple sclerosis and spinal muscular atrophy, a rare neurological disease. A drug it has been developing for Alzheimer’s is one of the most-watched, and controversial, medicines in development.

The meeting, held Feb. 26-27 at a Marriott hotel in Boston, has so far been linked with eight cases of Covid-19 overall, five of them in Massachusetts, according to the Boston Globe, [see https://www.bostonglobe.com/2020/03/05/metro/tennessee-coronavirus-patient-had-traveled-boston/ ] making it among the larger U.S. coronavirus clusters reported to date. The meeting was an annual gathering of executives at the vice president level or higher to discuss the company’s strategy.

On Friday, health officials were in the process of testing people who attended the gathering. Many had traveled to Boston for the event from outside Massachusetts, including Europe.

Vounatsos and other Biogen executives attended a health care investor conference in downtown Boston sponsored by the investment bank Cowen on Monday, March 2, just days after Biogen’s senior leadership meeting. Biogen has been in contact with Cowen about the potential coronavirus exposure, a Cowen representative confirmed to STAT.

The Cowen representative said the company was told by Biogen that none of the Biogen executives present, including Vounatsos, have been diagnosed with Covid-19.

According to the Centers for Disease Control and Prevention, transmission from asymptomatic people is not thought to be the main way the novel coronavirus spreads.

A biotech meeting at a hotel in downtown Boston appears to be the source of a cluster of the coronavirus in the U.S. — and a warning for employers who are still holding big gatherings as the outbreak spreads.

Seventy-seven of the 95 confirmed cases in Massachusetts have been linked to a meeting of executives with Biogen, a company based in Cambridge, next to Boston, that develops therapies for neurological diseases, state officials said.

An additional 12 people who have tested positive for the virus outside Massachusetts have been linked to the Feb. 26-27 meeting, including five in North Carolina, two in Indiana, and one each in New Jersey, Tennessee and Washington, D.C., officials said. Two tested positive in Europe, Biogen spokesman David Caouette said Wednesday.

The Biogen cluster underscores the danger in continuing to host business gatherings as the virus, which has sickened tens of thousands of people since emerging in China in December, spreads, said Marc Lipsitch, a Harvard University infectious disease epidemiologist.

"We need to stop having meetings like that," he said, noting a smaller cluster had been linked to a business conference at the Grand Hyatt in Singapore in January. "I think a lot of companies have concluded that on their own."

The Boston conference gathered roughly 175 company executives for two days of meetings at the Marriott Long Wharf hotel, a striking brick landmark on the city's scenic harborfront.

State health officials say the company notified them of the potential outbreak March 3 and that by March 6 they had publicly confirmed the cases as the type of coronavirus that causes the disease COVID-19. The disease usually exhibits mild or moderate symptoms, such as fever and cough, but it can be worse in older adults and people with other health problems.

State and city health officials said Wednesday they are working with the U.S. Centers for Disease Control and Prevention to identify close contacts of the people with confirmed cases in order to monitor them.

But they declined to say whether any of those sickened from the conference have been hospitalized, or how many of those quarantined in Massachusetts are linked to the meeting.

Local officials also declined to say whether they were taking additional steps, such as additional sanitizing or visitor restrictions at nearby landmarks, which include a ferry wharf, the New England Aquarium, and historic Faneuil Hall and its shopping and dining complex.

Several Biogen workers are "doing well," CEO Michel Vounatsos told employees Monday, while others are "fighting this novel virus and living in isolation from their families."

"Knowing they are in pain, hurts each of us," he wrote. "I am grateful for the courage our team has shown in this challenging time, working late into the night and in constant communication with public health partners."

The company, which has about 7,500 employees globally, said Friday it has asked employees who attended the meeting to quarantine themselves. It has also directed office-based workers in Massachusetts; Research Triangle Park, North Carolina; and Baar, Switzerland, to work from home, though manufacturing activities are continuing, Caouette said.

Most people recover. People with mild illness do so in about two weeks, while those with more severe illness may take three to six weeks to recover, according to the World Health Organization, which on Wednesday declared the worldwide outbreak a pandemic.

Massachusetts Public Health Commissioner Monica Bharel said this week that officials are still testing people potentially linked to the Biogen cluster and that there could be more who show symptoms.

Several Biogen employees who tested positive attended at least one other conference downtown, but there have so far been no cases reported among those participants, Daniel Gagnier, a spokesman for Cowan and Co., the New York-based investment bank that hosted the event, said Wednesday.

The Cowan event took place March 2-4 at the Marriott Copley Place, a hotel in a mall complex near the finish line of the Boston Marathon, which takes place in April. Officials have said they so far still intend to host the race.

A Marriott spokeswoman said Wednesday that the company is working closely with health officials. Massachusetts has one of the nation's largest clusters of the virus after Washington state, California and New York. In addition to the 95 cases in Massachusetts, nearly 450 people are currently in quarantine and more than 600 have completed the monitoring period symptom-free, officials said.

A Massachusetts scientist has been spared jail time by a Beijing court after she flew from the United States to her native China last March while infected with COVID-19 and not telling the airline - while covering up her symptoms with medication.

Jie Li, a 38-year-old statistician who worked at the Boston-area biotechnology firm Biogen, was given a suspended one-year prison sentence by a court in Beijing’s Shunyi District, CNNhas reported.

At the start of the coronavirus pandemic last March, Jie Li, a mother-of-one who was living with her husband in Belmont, Massachusetts, reported feeling ill with fever, fatigue, and other signs of COVID-19.

According to Chinese authorities, Jie Li claimed she started experiencing chills on March 1 and visited a doctor in Massachusetts two days later.

She was given Roche’s Tamiflu, an influenza medication, and then sent home, according to Fierce Pharma.

In the days and weeks that followed, Jie Lie continued to feel sick. She underwent two chest scans - one on March 5 and the other on March 10. 

Both showed no abnormalities, but another scan performed on March 11 returned with signs of lung infection. 

Jie Li tested for the virus on March 11, but decided to return to China with her family before the test result returned.

Jie Li and her family flew from Boston to Los Angeles, and then boarded a Air China flight CA988 bound for Beijing on March 12.

‘In order to board the plane, Jie Li took febrifuge to lower her body temperature before boarding, and passed the body temperature checks,’ the district court verdict said.

‘After boarding, when the flight required passengers to declare fever and other uncomfortable symptoms, Jie Li did not declare and did not truthfully answer the crew's inquiries about physical condition, contact history, and accompanying personnel.’

Before the aircraft landed, Jie Li, who was asymptomatic at the time she boarded, started to once again show signs of illness. 

She then acknowledged to the flight crew that she was experiencing symptoms consistent with COVID-19.

After she and her family landed in Beijing on March 13, she was immediately rushed to a local hospital for treatment, where she was diagnosed with COVID-19, according to the court.

Jie Li, her family, and some 60 other people who were in close contact with them were placed into quarantine.

Chinese law enforcement officials launched an investigation and charged Jie Lie with ‘the crime of obstructing the prevention and control of infectious diseases.’

The suspended sentence is considered light given that she faced a maximum penalty of seven years in prison. 

Jie Li was 37 years old at the time she was infected. An associate director for biostatistics, she worked on the Alzheimer’s drug team for the Cambridge, Massachusetts-based biotechnology firm Biogen.

Biogen, the multinational firm that is considered one of the pioneers in researching treatments for Alzheimer's and other neurological diseases, was at the center of a viral outbreak in the early weeks of the pandemic.

On February 26, the company held a leadership conference at the Boston Marriott Long Wharf hotel, where some 175 Biogen executives from around the world gathered for an annual meeting.

Jie Li did not attend the conference, but her boss, with whom she was in frequent contact, was at the event, which was later determined to be a coronavirus 'super spreader.' 

Within days, dozens of those who were at the conference reported feeling sick. At least 97 company executives were later confirmed to have been infected with coronavirus, according to The Boston Globe. 

Some of the earliest known cases in Tennessee, Indiana, and North Carolina were traced back to the Biogen conference in Boston.

Jie Li is a Chinese citizen from Chongqing, a megacity of some 30 million people.  According to her LinkedIn page, she studied at the University of Science and Technology of China.

She obtained permanent residency in the United States where she pursued an academic career in the field of biostatistics.

In 2009, she earned a PhD in spatial statistics from the University of Iowa. She then went to work for the pharmaceutical giant Eli Lilly for a year-and-a-half followed by a six-month stint at Merck, where she was employed as a biometrician.

In the summer of 2011, she joined Virginia Tech University's Department of Statistics. That fall, she taught at the school's public health program.

In 2015, she joined Biogen, where she worked for three years before leaving - only to return to the company in February 2019.

Jie Li's family purchased their home in Belmont, Massachusetts, a suburb west of Boston, in 2015.    

After Jie Li abruptly left the country, Biogen announced that she was no longer employed at the firm.