The U.S. government has long advised that all babies be immunized against hepatitis B right after birth. But on Friday, a federal vaccine advisory committee voted to do away with that recommendation.

The group, whose current members were all appointed by Health Secretary Robert F. Kennedy Jr., recommends a dose at birth only for babies whose mothers test positive for the virus or whose infection status is unknown.

For other babies, it will be up to the parents and their doctors to decide. The committee voted to suggest that when a family decides not to get a newborn dose, then the shots should begin when the child is 2 months old.

A loud chorus of medical and public health leaders decried the decision, saying the hepatitis B vaccine prevents thousands of illnesses.

"I think that the RFK Junior inspired advisory committee for immunization practices doesn't understand certain critical aspects of hepatitis B virus and hepatitis B vaccine." said Dr. Paul Offit, a Children’s Hospital of Philadelphia vaccine researcher and former government adviser.

Hepatitis B is a serious liver infection that for most people lasts less than six months. But for some — especially infants and children — it can become a long-lasting problem that can lead to liver failure, liver cancer and scarring called cirrhosis.

In adults, the virus is spread through sex or through sharing needles during injection-drug use.

But it can also be passed from an infected mother to a baby. Offit said babies can also get it from relatively casual contact with someone who has chronic disease, such as touching a towel or toothbrush because the virus can live on surfaces for more than seven days at room temperature. Up to 90% of infants who contract hepatitis B go on to have chronic infections, meaning their immune systems don’t completely clear the virus.

Around 2.4 million people in the U.S. are estimated to have hepatitis B, and as many as half are unaware they are infected, according to the Centers for Disease Control and Prevention.

For decades, the nation's vaccine guidance has been influenced by a government-appointed panel of experts, the Advisory Committee on Immunization Practices. Its recommendations have usually been adopted as national guidance that is widely heeded by doctors.

In 1991, the committee recommended an initial dose of hepatitis B vaccine at birth. The guidance was modified a little over the years and currently suggests a dose within 24 hours of birth for all medically stable infants who weigh at least 4.4 pounds (2 kilograms), plus follow-up shots to be given at about 1 month and 6 months.

Why a dose right at birth? Health officials used to rely on screening expectant mothers to find babies that might have been exposed to the virus. But many cases were missed, experts say, partly because some women weren't tested or test results were incorrect.

Newborn hepatitis B vaccinations are widely considered to be a public health success story. Over about 30 years, cases among children fell from about 18,000 per year to about 2,200.

A collaboration of public health researchers, the Vaccine Integrity Project, this week released its analysis of more than 400 studies and reports spanning 40 years. The group concluded the newborn dose is safe and is an important reason U.S. pediatric hepatitis B infections have fallen.

Kennedy, a leading anti-vaccine activist before becoming the nation’s top health official, fired all 17 members of ACIP earlier this year and replaced them with a group that includes several anti-vaccine voices.

The panel raised concerns about giving a vaccine to a baby so early in life. Committee members also worried that in many cases, doctors and nurses don’t have full conversations with parents about the pros and cons of giving the vaccine to newborns.

Dr. James Campbell, vice chair of the American Academy of Pediatrics’ infectious diseases committee, called this week's meetings a “brazen attempt to sow fear and distrust in vaccinations that have saved countless lives.”

A recent report estimated that delaying the hepatitis B vaccine to 2 months could result in at least 1,400 hepatitis B infections in children and 480 deaths. The report — which has yet to be peer reviewed or published in a medical journal — estimated the toll would be higher if the first dose was given even later.

But the vaccine committee's most direct power comes over what's covered by the federal Vaccines for Children program, which pays for shots for uninsured children from low-income families. Hepatitis B shots often have been bundled into the final hospital bill for childbirth. So the new ACIP recommendation likely would not be an economic obstacle for the current practice continuing at many hospitals, said Dr. Sean O’Leary of the pediatrics academy. But he said the change may confuse and frighten parents.

Soon after the vote, some state and local officials said they don't plan to heed the panel's advice to delay vaccination. These included the governor of Massachusetts and health officials in Maryland, New York City and Santa Clara County, California. Milwaukee's health department said parents should continue talking to their doctors and “follow trusted sources like the American Academy of Pediatrics.”

The pediatrics group said it will continue to recommend routine hepatitis B vaccination for all newborns, with babies receiving a first dose within 24 hours of birth, a second dose at one to two months and a third dose at six months.

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