“When the infections start in a nursing home it has been very difficult to contain them and the idea is that the booster might help,” Grabowski said.

In late September, the Centers for Disease Control and Prevention recommended boosters six months after the primary COVID vaccination for people over 65 and those living in long-term care facilities. As of Oct. 24, 52% of Massachusetts nursing home residents had received a recall, state data showed. The CDC has also suggested that people working in such high-risk environments, including nursing homes, receive the extra blow.

The majority of Massachusetts nursing home residents and staff completed their first round of vaccinations in late February, more than eight months ago. Recent studies suggest that declining immunity can lead to more severe COVID cases and hospitalizations, especially in people who are already frail.

“We encourage [boosters], and we expect boosters to be a condition of employment at some point, ”said Lou Woolf, president of Hebrew SeniorLife, one of Massachusetts’ largest elderly care operators.

In July, with 84% of its staff already vaccinated, Hebrew SeniorLife was among the first Massachusetts nursing home companies to impose COVID vaccines on their staff by October 1. A week later, Governor Charlie Baker ordered most nursing home workers to be fully vaccinated against the coronavirus by October 10.

CDC data shows that Massachusetts is second behind Rhode Island in COVID vaccinations for nursing home staff, with more than 96% having completed the previous cycle in two doses.

“Since February, successful efforts to provide this life-saving vaccine to workers and residents have resulted in a 73% drop in long-term care facility cases and nearly 100% deaths,” the Baker administration said. in a press release.

He also said he “actively supports” nursing home booster injections with on-site mobile clinics and other services. But the state does not impose boosters for the moment.

State data shows that the handful of facilities reporting new staff infections on a daily basis have increased since late October to a dozen facilities on certain days among the state’s approximately 380 nursing homes. Infections of residents remain infrequent.

Recent cases of COVID-19 at the Plymouth Rehabilitation & Health Care Center illustrate how declining immunity can expose facilities to a serious outbreak. A resident who had previously refused to be vaccinated was briefly hospitalized in late September and tested positive at the nursing home days later, according to Tim Brown, a company spokesperson.

Since then, at least 34 residents and 27 staff have been infected, and at least one resident has died, state data shows.

“We believe that boosters are a major tool for both preventing and mitigating the spread, and we continue to urge fully vaccinated residents and staff to receive boosters as soon as they become eligible,” Brown said in a statement. communicated. He did not have data on the number of residents and staff who received booster injections.

Meanwhile, Dr. Asif Merchant, medical director of four nursing homes in the Western Metropolitan area, hears the reluctance of some nursing home staff to receive a callback.

It’s “a little strange in some ways, because they’ve already received the blow twice,” he said.

Merchant, who is also a partner of a company that runs medical services for 45 nursing homes in Massachusetts, said some workers were telling him they had had enough of the vaccines. Others think they no longer need protection, he said.

A number of studies have concluded that people who have been vaccinated are significantly more protected against serious illnesses due to COVID than those who have not been vaccinated. While vaccinated people can still pass the virus on to others, research suggests the time period in which they can infect others is shorter than in those who are not vaccinated.

A growing body of research also suggests that protection against COVID vaccines wears off over time. A recent study published in the Journal of the American Medical Association analyzed the results of 1,197 patients hospitalized with COVID-19 between March and July of this year in 18 states. It found that vaccine breakthrough cases requiring hospitalization were most common in older patients with chronic illnesses – essentially the same population found in nursing homes.

And specifically for people vaccinated with Pfizer injections, those primarily used in nursing homes earlier this year, protection against hospitalization with COVID declined after four months, according to the study.

“The writing is on the wall: we see a decrease in the efficacy of the vaccine ‘, said Dr Michael Klompas, infectious disease physician and hospital epidemiologist at Brigham and Women’s Hospital.

Klompas said it is too early to know whether the booster injections will prevent the transmission of COVID among those who receive the additional injection, but he said this would be “consistent with everything we’ve seen about how boosters work. “. He favors shooting “for anyone at this stage of the pandemic”.

Massachusetts nursing homes are taking “extraordinary precautions” to protect residents from COVID-19, said Tara Gregorio, president of the Massachusetts Senior Care Association, a professional group of nursing homes. She said staff constantly wear face masks and other protective gear and are tested at least once a week. They also, she said, strongly encourage visitors to get vaccinated and take routine tests.

But Gregario said the biggest threat to the safety of residents right now isn’t necessarily the lack of recalls, but the critical shortage of personnel in the industry. Nursing home administrators feared state and federal COVID vaccine mandates for staff would prompt many to quit. That hasn’t happened, although some admins say they’ve lost a few over the course of tenure and fear that a required recall may be the tipping point.

“When you already have a staff shortage, even if you are talking about 2 to 3% [quitting], it can still have a huge impact, ”said Adam Berman, president and CEO of Legacy Lifecare, which includes five nursing homes. The company has resigned a few people because of the tenure, he said. Berman also said about 25% of its staff have received recalls, but they expect that number to increase as the company offers more recall clinics.

Klompas, the infectious disease doctor, predicted that booster vaccination warrants will come for nursing homes – but not before data begins to show a growing number of infections due to waning immunity in establishments.

“With public health policy,” he said, “are you reacting? Or are you anticipating?

Kay Lazar can be reached at kay.lazar@globe.com Follow her on Twitter @GlobeKayLazar.