A federal vaccine panel handpicked by Health and Human Services Secretary Robert F. Kennedy, Jr., voted Friday to stop recommending immediate immunization for all newborns against hepatitis B, a dangerous virus that leads to chronic liver disease in more than 90% of infected infants.

Earlier this year, Kennedy — a longtime vaccine skeptic who nonetheless vowed during his confirmation hearings not do anything that “makes it difficult or discourages people from taking vaccines” — fired all 17 previous members of the Advisory Committee on Immunization Practices (ACIP), replacing them with people who share his views and mostly lack experience in vaccine research or clinical practice.

Kennedy’s panel delayed three previous attempts at a vote amid “divisiveness and dysfunction,” according to the New York Times. On Friday, the panelists voted 8-3 that women who test negative for the hepatitis virus should consult with their health care provider and “decide when or if their child will” be vaccinated. These parents and their providers should “consider vaccine benefits, vaccine risks, and infection risks” and administer the shot “no earlier than 2 months of age,” the panel added.

The panel did not change the existing recommendation to immunize newborns of mothers known to be infected, or whose status is unknown.

Experts objected to the new guidance, noting that hepatitis B shots have nearly eliminated cases among newborns in the U.S. — and that there is no evidence they harm anyone.

“We know it’s safe, and we know it’s very effective,” said Dr. Cody Meissner, a professor of pediatrics at Dartmouth Geisel School of Medicine. But now “we will see more children and adolescents and adults infected with hepatitis B.”

Here’s everything you need to know to make sense of the change.

Where did this change come from?

Beyond just claiming that babies get too many vaccines and that the current vaccine schedule must be unhealthy somehow — a claim the American Academy of Pediatrics describes as “dangerous and inaccurate” — anti-vaccine critics have specifically zeroed in on hepatitis B because of how it tends to be transmitted.

“Hepatitis B is sexually transmitted, there is no reason to give a baby that is almost just born hepatitis B,” President Trump said in September. “So I would say wait til the baby is 12 years old and formed.”

Critics have also suggested that the risk of “infection throughout your early stage of life, and probably throughout most of your childhood, is extremely low,” as Retsef Levi, an ACIP panelist and a professor of operations management at Massachusetts Institute of Technology, put it on Friday. “To quantify how low it is, it’s probably one in several millions.”

Why vaccinate all newborns against hepatitis B?

Experts say the panel’s reasoning is flawed.

First of all, testing isn’t fool-proof. Each year, more than 17,000 infants are born in the U.S. to women who have hepatitis B. But nearly one in five pregnant women are not tested for the virus, and only about one in three women who test positive receive care, according to a report released on Tuesday by the Vaccine Integrity Project.

Overall, about half of the people infected with hepatitis B don't know they have the virus.

And even if a mother does test negative, her child can still get hepatitis B. Before the U.S. began universally vaccinating newborns against hepatitis B in 1991, about 18,000 children a year would become infected before the age of 10. Only half of those infections came from the mother at birth. The rest got infected somewhere else.

"There have been cases of infections in daycare,” Dr. Andrew Pavia, a professor of pediatrics and medicine with the University of Utah and a pediatric and adult infectious disease specialist, recently told NPR. “There have been cases of infection on sports teams. There have been documented infections from shared toothbrushes and from shared razors.”

That’s 9,000 children who would be missed under the new guidance.

The risks of childhood hepatitis B infection are too serious to ignore, experts say — even if cases are rare. Only 5% of people who are infected as adults develop chronic hepatitis B. But that number skyrockets to 90% among infants. The result? A heightened lifetime risk of cirrhosis, liver failure and liver cancer. About 25% of children who develop chronic hepatitis B end up dying of their infection.

“As a liver doctor who has treated patients with hepatitis B for decades, this change to the vaccine schedule is a mistake,” U.S. Senator Bill Cassidy of Louisiana, a Republican and a physician, wrote on X. “The hepatitis B vaccine is safe and effective. The birth dose is a recommendation, NOT a mandate.  … Ending the recommendation for newborns makes it more likely the number of cases will begin to increase again. This makes America sicker.”