The Centers for Disease Control and Prevention on Thursday officially endorsed booster shots for both the Moderna and Johnson & Johnson Covid-19 vaccines, one day after the Food and Drug Administration authorized the additional shots.

“These recommendations are another example of our fundamental commitment to protect as many people as possible from Covid-19,” CDC Director Rochelle Walensky said in a statement Thursday evening. “The evidence shows that all three Covid-19 vaccines authorized in the United States are safe — as demonstrated by the over 400 million vaccine doses already given. And, they are all highly effective in reducing the risk of severe disease, hospitalization, and death, even in the midst of the widely circulating Delta variant.”

The CDC also wholeheartedly endorsed a “mix and match” approach to vaccine boosters, meaning the booster shots that people get do not need to match the ones they got for their initial vaccinations.

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Taken together, the recommendations greatly expand access to booster shots.

The director recommended a booster six months or more after receiving Pfizer or Moderna vaccine for people 65 and older and adults 18 and older who live in long-term care settings, have underlying medical conditions or work or live in high-risk settings.


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The CDC said that adults 18 and older who have received the Johnson & Johnson vaccine may receive any booster at least two months later.

Officials said all three vaccines are effective and did not endorse any particular combination over another. However, evidence was presented earlier this week from a National Institutes of Health study that found that a booster of either Pfizer’s or Moderna’s mRNA vaccine after a Johnson & Johnson dose raised antibody levels more than two doses of the Johnson & Johnson vaccine.

Nearly 190 million people in the U.S. are fully vaccinated. Overall, the vaccines have proven to be safe. Still, a few rare side effects have been identified, leading to concerns among some of the committee members that an additional dose would raise risk further.

In particular, the Pfizer and Moderna vaccines have been linked with rare cases of heart inflammation called myocarditis in men under 30. The Johnson & Johnson vaccine has been linked to a risk of rare but serious blood clots in women under 50.

Because of those safety issues, a committee member, Dr. Helen Keipp Talbot, an associate professor of medicine at Vanderbilt University Medical Center in Nashville, Tennessee, said the ability to mix and match was “priceless.”

It gives young women who got the Johnson & Johnson vaccine and are at increased risk for blood clots the ability to get an mRNA booster, Talbot said. “I was wondering if in the clinical guidance it could recommend that young women not get [this vaccine], that they look at other vaccines as their second dose,” she said.

Similarly, young men can potentially switch to Johnson & Johnson boosters because of the increased risk of myocarditis from the mRNA vaccines, she said.

Who can get a booster?

More than 11 million people have already received booster shots, according to the CDC. Some are people with compromised immune systems who have been eligible for boosters since August. Others are those who qualified for booster doses of the Pfizer vaccine, which was authorized last month.

Tens of millions more are now eligible for the shots, including the nearly 15 million people who were initially vaccinated with the Johnson & Johnson vaccine.

Whether people are eligible for booster shots depends on which vaccine they initially received.

For people who were initially vaccinated with the Johnson & Johnson vaccine, there are no limits on who can get boosters, as long as it is has been at least two months since an initial vaccination. That is, anyone who got the Johnson & Johnson shot would now be able to get any of the three vaccines as boosters.

People initially inoculated with the Moderna or Pfizer vaccines can also get any of the three vaccines as boosters six months after they were initially vaccinated, but there are limits to who is eligible: adults ages 65 and older, those living in long-term care facilities, people with underlying health conditions and those whose jobs put them at higher risk for Covid-19 exposure.

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While the committee members voted unanimously in favor of both booster shots, there were significant concerns about the benefits of additional doses during the daylong meeting.

A committee member, Dr. Sarah Long, a professor of pediatrics at Drexel University College of Medicine in Philadelphia, stressed the importance of following the science, noting the lack of evidence that people under age 50 need booster shots.

Indeed, although vaccine effectiveness has been shown to wane in older adults, it appears to remain robust in younger people.

Another committee member, Dr. Wilbur Chen, a professor of medicine at the University of Maryland School of Medicine, agreed. “I think we’ve already discussed that there is data that there are some people that really don’t need the booster doses this time,” he said.

Dr. Jason Goldman, who is not a committee member but attended the meeting as a liaison for the American College of Physicians, said that regardless of whether people need boosters, many people are deciding on their own to get them.

“The reality is they’re not consulting with their physicians in all cases,” he said. “They’re just going out and getting booster doses.”

After the meeting, Glen Nowak, a co-director of the University of Georgia’s Center for Health and Risk Communication, said communicating who should get boosters to the general public will be “challenging.”

“You are going to probably hear people say, ‘Go talk to your provider,’” he said, “but based on today’s conversation, I don’t know that providers are going to be as equipped or better equipped to be able to have those conversations.”

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