You’re not eligible yet for a COVID-19 booster. Should you be worried?

Not eligible yet for a booster? Experts say don't worry, you're protected. Eligibility may also be widened as soon as next month.Lane Turner/Globe Staff

Millions of people still can’t get a COVID-19 vaccination booster, remaining ineligible because they fall outside the new guidelines approved by federal regulators. But experts say if you find yourself in that position, don’t worry too much about getting that extra shot.

“I think it’s normal and natural to have this kind of FOMO,” said Dr. Cassandra Pierre, an infectious disease physician who is the associate hospital epidemiologist at Boston Medical Center. But, she said: “You have really good immunity still from your primary vaccination series. We knew that the vaccines were safe and effective, and that has continued to be true.”

With the latest approval by regulators last week, people can now get Pfizer or Moderna boosters if they are six months past their full two-dose vaccination and they’re 65 or older, have certain medical conditions, or live in long-term care settings. They also qualify for a booster if they live or work in a wide variety of settings that put them at higher risk of catching COVID-19, including health care facilities, schools, prisons, and homeless shelters.

(The regulators also approved a booster for all recipients of the less common one-dose Johnson & Johnson vaccine who are two months past the date of their shot. And they gave the green light for “mixing and matching,” allowing people to choose a different booster from the one they originally received.)

Pfizer and Moderna recipients who aren’t yet eligible for a third shot should know that they still are protected against severe disease, hospitalization, and death, the experts stress.

Though there appeared to be a lessening of protection against mild disease, Pierre said, “The breakthrough infections that have led to hospitalizations and severe complications have been generally mostly experienced by individuals who were either elderly or had underlying medical conditions, including being immunocompromised” — groups of people who are already eligible for booster shots.

Dr. Richard Ellison, an infectious disease physician who is the hospital epidemiologist at the University of Massachusetts Medical Center in Worcester, explained that vaccines immediately spur production of antibodies against the virus, but there is also a “memory built in to our immune system” that provides longer-term protection after the antibodies decline.

People who have had only two shots but are otherwise healthy may not be as protected as they once were against mild COVID-19, but they are “getting really good, persistent protection” from more severe disease, he said. “Prior vaccination is going to still protect you from getting sick and dying.”

Still, an underlying frustration that you can’t yet get the third shot is understandable, doctors acknowledge. Dr. Shira Doron, an infectious disease physician who is the hospital epidemiologist at Tufts Medical Center, said, “I totally get why many people are disappointed that they don’t qualify for boosters,” including the worry that a mild case might get severe and the disruptions that a mild case will cause to a person’s life by requiring them to isolate themselves and their loved ones to quarantine.

She noted that the experts advising the federal regulators on their recent decisions didn’t all agree that the boosters needed to be authorized for such a large swath of people. “I think it’s fairly unanimous agreement that it’s beneficial for people over the age of 65. I think outside of that, it’s pretty unclear,” she said.

So what would she say to those who aren’t yet authorized? “I guess I would say, you know, many experts believe you don’t need a booster, and that’s why it’s not approved. And the reason you don’t need it is because you’re at extremely low risk of anything other than a mild upper respiratory tract infection,” Doron said.

Doron said an underlying question in the debate over boosters is whether the goal of vaccination is “sterilizing immunity,” which prevents all infections, or the prevention of severe disease, hospitalization, and death. “We haven’t agreed upon that as a society,” she said.

But the fact remains that people may have to get used to the virus being around and causing mild disease. “We have to learn to live with this virus,” she said. “We have to move forward. This booster program may bring down some of the risk of mild infection, and then we don’t know if it’s going to be a long-lived prevention of mild infection, or if it’s just going to last few months again and then drop down.”

For those still worried about not getting a booster shot, there may be some good news ahead in the coming weeks. Several news outlets reported last week, based on sources, that the booster eligibility age could be lowered to 40. The authorization could occur next month, two federal officials told the Washington Post, speaking on condition of anonymity because they were not authorized to discuss the issue.

The expanding authorizations are consistent with statements by President Biden that he wants all Americans to get a booster shot. At a news conference last month, Biden said the administration was “looking to the time when we’re going to be able to expand the booster shots, basically, across the board.”

In the meantime, people who are worried and still waiting can take simple precautions, like social distancing, wearing masks, and recognizing the higher risk posed by indoor spaces, experts said.

Looking ahead to the holidays, Pierre said people should evaluate their risks and consider steps to reduce them, such as not inviting unvaccinated people to gatherings, opening windows to improve ventilation, and using rapid tests. If people are traveling, they should consider whether they want to go to areas where COVID-19 rates are high.

“There are ways to protect ourselves without giving up a lot of the good things in our lives,” she said.