A woman receives a COVID-19 vaccine at a clinic in Philadelphia

A woman receives a COVID-19 vaccine at a clinic in Philadelphia, Penn., May 18, 2021.

WASHINGTON — Advisers to the Centers for Disease Control and Prevention endorsed a coronavirus booster-shot-for-all policy Friday, voting 10-1 to allow all adults to get an extra shot of the Pfizer-BioNTech or Moderna vaccines. In a separate vote, they recommended the shots for all people 50 or over.

CDC Director Rochelle Walensky was expected to sign off on the recommendations later Friday, making broad booster eligibility official U.S. policy a week before Thanksgiving, the unofficial start of holiday season and as infections tick up in large swaths of the country. Fearful of winter surges, officials of about a dozen states already have already moved on their own to broaden booster eligibility to those 18 and older amid strong evidence that vaccine immunity wanes over time across all age groups.

“Simplifying eligibility will allow staff across the states, territories and local health departments to focus on making vaccination — primarily the primary vaccination series — as easy and as accessible as possible,” said Nirav Shah, director of Maine’s Center for Disease Control and Prevention.

Health officials and experts hope that straightforward federal recommendations will eliminate confusion about eligibility and prompt millions to get the shots before they travel or gather with friends and family.

Until now, the recommendations for boosters were “muddled beyond saving at this point,” said Jason Schwartz, associate professor of health policy at the Yale School of Public Health. States tried to fill the void, he said, but going forward, health officials need to underscore the urgency of boosters for the most vulnerable — those 65 and older and those in nursing homes. That message, he said, has gotten “lost in a sea” of complicated recommendations, he said.

Only about 38% of fully vaccinated people over 65, and 18% of all adults have gotten boosters, including those with weakened immune systems, such as cancer patients and organ transplant recipients who need an extra dose to be fully vaccinated, according to the CDC.

The action by the Advisory Committee on Immunization Practices follows the authorization of the two vaccine boosters for all adults Friday morning by the Food and Drug Administration. The actions make official what has been taking place on the ground, where many consumers who wanted the shots were able to get them by saying they fell into one of the eligible groups. Millions more stayed on the sidelines, however, either because they believed that they didn’t need the shots or they didn’t qualify for them.

In the past, some panel members had questioned the benefit of offering boosters to healthy young people, especially since the two mRNA vaccines are linked to an extremely rare risk of inflammatory heart problems, such as myocarditis, largely in males.

But data on side effects from boosters presented for the first time Friday provided reassuring information. Preliminary information from one vaccine safety monitoring system showed that of 26 million mRNA boosters given in the United States, there were a dozen confirmed reports of myocarditis, and another 38 pending investigation, said Tom Shimabukuro, a CDC vaccine safety official. The median age of the dozen confirmed with myocarditis is 51. Ten were discharged from the hospital and six recovered from symptoms, he said.

Data from Israel, where nearly 4 million booster doses have been given to those 12 and older since August, shows lower rates of side effects and other reactions after people received booster doses than after doses one or two.

Meanwhile, researchers are seeing stronger evidence of waning immunity among older adults and long-term care facility residents, many of whom were among the first to be vaccinated earlier this year, Walensky noted at a White House briefing this week.

Unvaccinated people are at highest risk, she said, but “we are seeing an increase in emergency department visits among adults 65 and older, which are now again higher than they are for younger age groups.”

Until Friday, boosters were recommended for people 65 or older who had received their second Pfizer or Moderna shots at least six months ago, as well as for other adults at high risk of COVID-19 because of health problems or their job or living conditions. Boosters were also recommended for all adults who received the single-dose Johnson & Johnson vaccine at least two months ago.

The majority of COVID-19 hospitalizations and deaths are among unvaccinated people, but the United States is seeing “inklings” of waning protection against severe infection, Anthony Fauci, President Biden’s top coronavirus medical adviser said this week.

“What we’re starting to see now is an uptick in hospitalizations among people who’ve been vaccinated but not boosted,” Fauci told NBC News. “It’s a significant proportion, but not the majority by any means.”

While some experts, including Fauci, have argued that giving extra shots to the fully vaccinated will help control the pandemic by reducing transmission, getting unvaccinated people their first shots would have the biggest impact. Some experts and panel members worry that all the attention to boosters may detract from efforts to reach the 60 million Americans who are eligible for vaccinations but haven’t gotten the shots.

Data from the CDC indicates that more than two-thirds of shots being administered in the United States over the last week are for boosters and new shots for children ages 5 to 17, according to data published Nov. 11 through Nov. 18. Of the 11.8 million vaccinations given during that time, just over half were boosters shots. More than 70% of the boosters went to people age 50 and older. More than one-third of the non-booster shots went to children age 5 to 17, according to CDC data. About 3.5 million shots went to first or second vaccinations for adults.

John Brownstein, chief innovation Officer at Boston Children’s Hospital, whose VaccineFinder website powered the U.S. governments coronavirus site Vaccines.gov, said he has not seen a sudden increase in demand for boosters as states have gone their own way to broaden eligibility.

“The slope of increase hasn’t changed,” Brownstein said, with about 20% of fully vaccinated people now boosted. He anticipated a potential change next week ahead of holiday travel, even as he worried that conversations around boosters can muddy messaging around primary vaccination campaign.

“This is where the complicated nuance comes in,” Brownstein said.

The Washington Post's Dan Keating contributed to this report.