By Arthur Allen, KFF Health News

Everyone over the age of 6 months should get the latest covid-19 booster, a federal expert panel recommended Tuesday after hearing an estimate that universal vaccination could prevent 100,000 more hospitalizations each year than if only the elderly were vaccinated.

The Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices voted 13-1 for the motion after months of debate about whether to limit its recommendation to high-risk groups. A day earlier, the FDA approved the new booster, stating it was safe and effective at protecting against the covid variants currently circulating in the U.S.

After the last booster was released, in 2022, only 17% of the U.S. population got it — compared with the roughly half of the nation who got the first booster after it became available in fall 2021. Broader uptake was hurt by pandemic weariness and evidence the shots don’t always prevent covid infections. But those who did get the shot were far less likely to get very sick or die, according to data presented at Tuesday’s meeting.

The virus sometimes causes severe illness even in those without underlying conditions, causing more deaths in children than other vaccine-preventable diseases, as chickenpox did before vaccines against those pathogens were universally recommended.

The number of hospitalized patients with covid has ticked up modestly in recent weeks, CDC data shows, and infectious disease experts anticipate a surge in the late fall and winter.

The shots are made by Moderna and by Pfizer and its German partner, BioNTech, which have decided to charge up to $130 a shot. They have launched national marketing campaigns to encourage vaccination. The advisory committee deferred a decision on a third booster, produced by Novavax, because the FDA hasn’t yet approved it. Here’s what to know:

Who Should Get a Booster Shot?

The CDC advises that everyone over 6 months old should, for the broader benefit of all. Those at highest risk of serious disease include babies and toddlers, the elderly, pregnant women, and people with chronic health conditions including obesity. The risks are lower — though not zero — for everyone else. The vaccines, we’ve learned, tend to prevent infection in most people for only a few months. But they do a good job of preventing hospitalization and death, and by at least diminishing infections they may slow spread of the disease to the vulnerable, whose immune systems may be too weak to generate a good response to the vaccine.

Pablo Sánchez, a pediatrics professor at The Ohio State University who was the lone dissenter on the CDC panel, said he was worried the boosters hadn’t been tested enough, especially in kids. The vaccine strain in the new boosters was approved only in June, so nearly all the tests were done in mice or monkeys. However, nearly identical vaccines have been given safely to billions of people worldwide.

When Should You Get It?

The vaccine makers say they’ll begin rolling out the vaccine this week. If you’re in a high-risk group and haven’t been vaccinated or been sick with covid in the past two months, you could get it right away, says John Moore, an immunology expert at Weill Cornell Medical College. If you plan to travel this holiday season, as he does, Moore said, it would make sense to push your shot to late October or early November, to maximize the period in which protection induced by the vaccine is still high.

Who Pays For It?

When the ACIP recommends a vaccine for children, the government is legally obligated to guarantee kids free coverage, and the same holds for commercial insurance coverage of adult vaccines.

For the 25 to 30 million uninsured adults, the federal government created the Bridge Access Program. It will pay for rural and community health centers, as well as Walgreens, CVS, and some independent pharmacies, to provide covid shots for free. Manufacturers have agreed to donate some of the doses, CDC officials said.

Will New Booster Work Against Current Variants?

It should. More than 90% of currently circulating strains are closely related to the variant selected for the booster earlier this year, and studies showed the vaccines produced ample antibodies against most of them. The shots also appeared to produce a good immune response against a divergent strain that initially worried people, called BA.2.86. That strain represents fewer than 1% of cases currently. Moore calls it a “nothingburger.”

Why Are People Still Skeptical About Vaccines?

Experience with the covid vaccines has shown that their protection against hospitalization and death lasts longer than their protection against illness, which wanes relatively quickly, and this has created widespread skepticism.

Most people in the U.S. have been ill with covid and most have been vaccinated at least once, which together are generally enough to prevent grave illness, if not infection — in most people. Many doctors think the focus should be on vaccinating those truly at risk.

What About Getting Other Vaccines?

People tend to get sick in the late fall because they’re inside more and may be traveling and gathering in large family groups. This fall, for the first time, there’s a vaccine — for older adults — against respiratory syncytial virus. Kathryn Edwards, a 75-year-old Vanderbilt University pediatrician, plans to get all three shots but “probably won’t get them all together,” she said.

Covid “can have a punch” and some of the RSV vaccines and the flu shot that’s recommended for people 65 and older also can cause sore arms and, sometimes, fever or other symptoms. A hint emerged from data earlier this year that people who got flu and covid shots together might be at slightly higher risk of stroke. That linkage seems to have faded after further study, but it still might be safer not to get them together.

Pfizer and Moderna are both testing combination vaccines, with the first flu-covid shot to be available as early as next year. Although Pfizer’s shot has been approved in the European Union, Japan, and South Korea, and Moderna has won approval in Japan and Canada. Rollouts will start in the U.S. and other countries this week.

Unlike in earlier periods of the pandemic, mandates for the booster are unlikely. But “it’s important for people to have access to the vaccine if they want it,” said panel member Beth Bell, a professor of public health at the University of Washington.

“Having said that, it’s clear the risk is not equal, and the messaging needs to clarify that a lot of older people and people with underlying conditions are dying, and they really need to get a booster,” she said.

ACIP member Sarah Long, a pediatrician at Children’s Hospital of Philadelphia, voted for a universal recommendation but said she worried it was not enough. “I think we’ll recommend it and nobody will get it,” she said. “The people who need it most won’t get it.”

KFF Health News is a national newsroom that produces in-depth journalism about health issues.