Public health officials: Mass. has now had 3 cases of British coronavirus variant

The sun broke through the clouds as a woman stood on Westminster Bridge in London. The United Kingdom is under an indefinite lockdown to to curb the spread of the new coronavirus variant. Cases have begun to appear in the United States, including 3 in Massachusetts, according to the CDC.Kirsty Wigglesworth/Associated Press

The US Centers for Disease Control and Prevention says a third case of the British coronavirus variant has been detected in Massachusetts.

The new information came in an update Monday to a CDC page that now lists 293 cases across the United States.

The Massachusetts Department of Public Health, which reported the state’s second case last week, said the third case was detected in a woman in her 50s who lives in Worcester County who had a “known exposure.”

“Surveillance data so far indicates that the [British] variant is not widespread in Massachusetts but it is important to do everything possible to keep it from becoming widespread,” the department said in a statement.

The department said it plans to incorporate variant case counts in the state’s weekly coronavirus statistics report.

Health experts have warned that the British variant, which is believed to be more transmissible than the current version, will probably become the dominant source of infection in the United States by March. They worry it could cause an increase in the volume of cases, hospitalizations, and deaths. British authorities also have said there is evidence that the variant may be more deadly than the original.

The arrival of the variant has made it ever more urgent that people get vaccinated, experts say.

The CDC says it is monitoring the British variant, as well as other variants that have emerged in South Africa and Brazil.

“CDC, in collaboration with other public health agencies, is monitoring the situation closely. CDC is working to detect and characterize emerging viral variants and expand its ability to look for COVID-19 and new variants,” the CDC’s website says.

The only other New England state where the British variant has been detected is Connecticut, where four cases have been found. In New York, 22 cases have been found, according to the CDC.

Officials and experts said even before the first case was detected that they suspected the British variant was already in Massachusetts.

What should people do? The experts say that people should double down on precautionary measures, such as wearing masks, social distancing, and avoiding crowds. Getting millions of Americans vaccinated as quickly as possible is another key to stopping the virus.

Material from Globe wire services was used in this report.