By Nancy Lapid

Dec 5 (Reuters) -

A U.S. vaccine advisory panel on Friday

scrapped

its long-standing recommendation that all infants receive the hepatitis B vaccine at birth, handing Health Secretary Robert F. Kennedy Jr. a major policy victory that disease experts warn could erode decades of public health progress.

Here's what you need to know about the hepatitis B virus (HBV), available vaccines and the new recommendations.

WHAT IS HEPATITIS B?

Hepatitis B attacks the liver and is the leading cause of liver cancer worldwide. Many infected people do not have symptoms and do not realize they are infected. In most adults who acquire the virus, the infection resolves on its own. But it becomes chronic in more than 90% of infants and in up to 50% of young children who become infected.

Decades after infection, patients can develop liver failure and require a liver transplant. Because there is no cure for hepatitis B, patients often have recurrent liver disease after a transplant.

HOW COMMON ARE HBV INFECTIONS TODAY?

U.S. hepatitis B infection rates dropped nearly 90%, from about 9.6 per 100,000 before vaccination became widespread to approximately one per 100,000 in 2018.

The World Health Organization estimates that 254 million people worldwide were living with chronic hepatitis B infection in 2022, with 1.2 million new infections each year.

HOW IS THE VIRUS TRANSMITTED?

Hepatitis B is most often acquired through contact with body fluids from an infected person. It can also be transmitted via needlestick injury, tattooing and piercing.

WHY IS THE VACCINE GIVEN TO NEWBORNS?

Before widespread availability of the vaccine, transmission from mothers to babies during childbirth was the most common route of infection. In the U.S., before vaccines were available, roughly 85% of newborns became infected when mothers had active infections, as did approximately 30% of babies born to mothers with previous infections in whom the virus was inactive.

At present, 0.7% to 1.1% of infants born to such mothers develop infection after vaccination at birth, according to the U.S. Centers for Disease Control and Prevention.

Similar declines in infant hepatitis B infections have been seen elsewhere with widespread vaccination of newborns. Since 2020, the practice had been adopted by 190 of the 194 WHO member countries, according to a 2022 CDC report. More than half of those countries provide it to all newborns immediately after birth.

WHAT IS THE NEW RECOMMENDATION FOR HEPATITIS B VACCINE?

The vaccine committee voted to reserve the hepatitis B birth dose for infants whose mothers test positive for the virus or whose hepatitis B status is unknown. If accepted by the CDC, it will end the 1991 universal recommendation that has shielded U.S. children from infections.

For infants whose mothers test negative, the panel now recommends that parents, in consultation with a healthcare provider, should decide when or if to start the vaccine series.

Additionally, the panel backed the recommendation that parents, in consultation with a healthcare provider, test children for hepatitis B antibodies before deciding to give subsequent shots.

WHY TREAT ALL BABIES, NOT JUST THOSE WITH INFECTED MOTHERS?

Universal birth dosing protects infants whose parents' hepatitis B status is unknown or was not tested during prenatal care. Also, maternal testing can miss recent infections, making universal newborn vaccination more reliable.

Even when mothers are not infected, newborns can acquire hepatitis B from close contact with other infected individuals and caregivers.

WHAT'S KNOWN ABOUT ADVERSE REACTIONS?

The hepatitis B vaccine is widely regarded as safe. Side effects are typically mild, such as soreness at the injection site or a low-grade fever, while serious allergic reactions, including anaphylaxis, are extremely rare, according to the WHO.

(Reporting by Nancy Lapid, Mrinalika Roy, Padmanabhan Ananthan and Kamal Choudhury in Bengaluru; Editing by Michele Gershberg, Bill Berkrot and Maju Samuel)

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