What to know about hepatitis B infection and vaccination

By Deidre McPhillips, Jamie Gumbrecht, CNN

(CNN) — A group of independent vaccine advisers to the US Centers for Disease Control and Prevention is meeting this week, and a key item on the agenda is the hepatitis B vaccine.

After presentations about the hepatitis B disease and vaccine safety, the Advisory Committee on Immunization Practices, or ACIP, is expected to vote on whether to abandon the universal hepatitis B vaccine recommendation for infants.

What is hepatitis B?

Hepatitis B is a liver infection caused by a virus.

After an acute hepatitis B infection, many adults clear the virus. But acute infection can lead to chronic hepatitis B, which is linked to increased risk of liver cancer, organ failure and cirrhosis, or scarring over the liver. People with chronic hepatitis B are 70 to 85% more likely to die early.

At Thursday’s ACIP meeting, Dr. Sandra Fryhofer, speaking as liaison for the American Medical Association, said that she spent time treating patients in a hepatitis B ward as a medical student.

“Those were the sickest patients I had ever seen in my life,” she said. “I have treated patients that have liver disease from hep B, cirrhosis from hep B, liver cancer from hep B, and death from hep B.”

Infants and children who are infected with hepatitis B are more likely to develop chronic disease, including about 90% of infants and 30% of children ages 1 to 5.

How is hepatitis B spread?

The hepatitis B virus is extremely infectious. It is transmitted when blood, semen or another body fluid from a person infected with the virus enters the body of someone who’s not infected.

Certain medical conditions, behaviors and other factors increase an individual’s risk of acquiring hepatitis B — including injecting drugs and sexual activity — but anyone can get it. The hepatitis B virus can also be passed easily during childbirth from a pregnant woman to her child during either a vaginal delivery or C-section.

How common is hepatitis B?

Many people with hepatitis B do not have symptoms, and more than half may not be aware of their infection.

The latest data from the CDC shows that there were about 2,200 newly reported cases of acute hepatitis B in 2023, but estimates suggest that the actual number of cases was more than six times higher — closer to 14,400.

The CDC also estimates that about 640,000 adults in the US have chronic hepatitis B.

Globally, the World Health Organization estimates that 254 million people are living with chronic hepatitis B infection, with about 1.2 million new infections each year.

Can hepatitis B be treated?

There is no treatment for acute hepatitis B, but there are some medications that can be used to treat chronic cases. Treatment for chronic hepatitis B can be lifelong; there is no cure for the disease.

How can hepatitis B be prevented?

The best way to prevent hepatitis B infection is vaccination. The vaccines are highly effective at preventing infection in infants and for long-term protection into adulthood.

Most people who have hepatitis B were infected as infants or young children when their immune systems were not fully developed, according to the CDC. Currently, the agency recommends that all infants get vaccinated at the time of birth, before they leave the hospital.

Infants typically receive a three-dose series of the hepatitis B vaccine, and a review of scientific evidence by the Vaccine Integrity Project shows 95% of healthy infants have sufficient protection against an infection after the third dose. Vaccination has also been shown to decrease the risk of infection in infants born to mothers with hepatitis B by nearly 70%.

More than 90% of people who received the primary vaccine series had evidence of protection 30 years later, according to data on the CDC’s website.

Universal vaccination against hepatitis B was first recommended for infants in 1991, and the strategy has been credited with cutting the number of hepatitis B infections in kids from about 18,000 cases a year to an estimated 20 cases a year now. But anti-vaccine activists, including HHS Secretary Robert F. Kennedy Jr., have long questioned the necessity and safety of this vaccine, despite decades of evidence supporting it.

Women are also typically tested for hepatitis B during their first three months of pregnancy, but it’s possible to miss maternal infections if a woman catches the virus after she’s tested for it. Maternal testing also doesn’t protect babies from being exposed to other positive family members or caregivers.

“We established during the data that was presented today that our detection of these hepatitis B positive moms is not 100%, so we’ve got a gap there that certainly needs to be tightened up,” Fryhofer said at Thursday’s ACIP meeting. “We have a duty to protect these little babies, and I am particularly concerned about this early post-natal transmission.”

Infectious disease experts say vaccinating every baby provides a critical safety net to catch those at risk when maternal screening misses.

“When these little babies are born, between the time they’re born and when we might delay a hepatitis B dose, we don’t know who’s going to be taking care of them,” Fryhofer said. “Are we going to test every patient that has access to or touches that baby? I mean, that’s that’s not something that’s really doable.”

Is the hepatitis B vaccine safe?

The Vaccine Integrity Project’s scientific review found that administering the hepatitis B vaccine at birth has “consistently been demonstrated to be safe.”

Only “mild‑to‑moderate, short-term reactions” — such as redness and swelling at the injection site and low-grade fever — have been reported, and there was “no increased incidence of life-threatening vaccine‑related serious adverse events.”

Dr. Anthony Fiore, an infectious diseases physician and former CDC official who worked in the hepatitis division, called it a “remarkably safe vaccine” that had been studied many ways before and after it was licensed. The US’ vaccine safety monitoring systems “looked very carefully at this, chasing down concerns people might have about increased fevers or about other chronic conditions.

“None of these have panned out,” Fiore said. “Nothing has been shown that has any long-term consequences, and certainly nothing that has anywhere near the consequences of a chronic hepatitis B virus infection.”

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CNN’s John Bonifield and Brenda Goodman contributed to this report.