Congressman Stephen F. Lynch has tested positive for COVID-19, his office said Friday, making him the second member of the Massachusetts congressional delegation to report contracting the virus in roughly 24 hours.
Lynch received the positive test result Friday “after a staff member in the congressman’s Boston office had tested positive earlier in the week,” said Molly Rose Tarpey, a spokeswoman for the South Boston Democrat, in a statement.
Tarpey said Lynch “had received the second dose of the Pfizer vaccine and subsequently received a negative COVID-19 test prior to attending President Biden’s Inauguration. While Mr. Lynch remains asymptomatic and feels fine, he will self-quarantine and will vote by proxy in Congress during the coming week.”
She did not immediately respond to a question from the Globe as to when exactly Lynch received the second Pfizer shot.
Pfizer’s vaccine requires two injections, spaced three weeks apart. The vaccine has an efficacy rate of 52 percent between the first and second dose, according to the data assessed by the FDA. The efficacy of the vaccine climbs to 95 percent seven days after the second dose.
Public health experts say it takes about two weeks after the second dose to achieve the full immunity provided by the vaccine. Even then, researchers don’t yet know whether the vaccines prevent infection and transmission of the virus; they just know the vaccines should keep you from getting sick.
Lynch last week toured the Jamaica Plain VA Medical Center, one day after officials there confirmed that nearly 2,000 doses of the Moderna COVID-19 vaccine were spoiled when a cleaning contractor accidentally loosened an electric plug on a freezer.
Lynch’s announcement followed a revelation from Representative Lori Trahan that she tested positive for the coronavirus on Thursday. Trahan received her first dose of the coronavirus vaccine while in Washington last week, according to a spokesman. Trahan was the first member of the Massachusetts delegation to test positive for the virus.
Earlier this month, Conan Harris, the husband of Representative Ayanna Pressley of Boston, tested positive after both were locked down in the Capitol while supporters of former president Donald Trump stormed the building. At the time, Pressley tested negative.
A Pressley spokesman said the Boston Democrat was recently in isolation following her husband’s positive test, and has not come into contact with either Trahan or Lynch. Pressley, who also got the vaccine, “wishes Reps. Trahan and Lynch a quick recovery,” he said.
Several other members of the delegation, reached by the Globe Friday, said they had recently tested negative. Nor did any report close contact with Lynch.
Representative Jim McGovern, a Worcester Democrat, received his second vaccine dose on Jan. 5, a spokesman said. “He saw Congressman Lynch outside briefly on Inauguration Day, but he has not been in the same space since, and has not tested positive.”
Representative Katherine Clark, a member of House Speaker Nancy Pelosi’s leadership team, got her second dose on Jan. 11. The Melrose Democrat is tested regularly, “but will get an additional test as a precaution,” said a spokeswoman.
A spokeswoman for Senator Elizabeth Warren said the Massachusetts Democrat has not been in close physical contact with Lynch or Trahan in recent weeks. Warren also got vaccinated, receiving her second shot on Jan. 7, the spokeswoman said.
Representative Seth Moulton also has had both doses of the Pfizer vaccine, according to a spokesman. The Salem Democrat received his last negative COVID-19 test result on Jan. 19. Moulton plans to get tested Saturday morning “out of an abundance of caution,” the spokesman said.
Representative Jake Auchincloss, a Newton Democrat, has had both vaccine doses and recently tested negative, according to a spokesman. House Ways and Means Chairman Richard Neal also has recently tested negative and has received two doses of the coronavirus vaccine, a spokesman said.
Representative Bill Keating of Bourne “was with his colleagues last week, but is feeling fine,” a spokeswoman said in an e-mail Friday night. Keating sent his best wishes to his colleagues who have tested positive.
“I wish Lori and Steve a speedy recovery and look forward to seeing them soon,” he said in a statement.
Globe Correspondent Jeremy C. Fox contributed to this story.