Contributor: Vaccine confusion sets up U.S. for a resurgence of hepatitis B in babies

Measles is back in the United States. More than 1,500 cases have already been reported in the first months of 2026, which will allow the country to surpass last year’s total of more than 2,200, the highest number in decades. Public health officials warn that the country’s “measles-free” status is now at risk as childhood vaccination rates decline.

Measles may not be the only disease poised to make a comeback. Another virus that once infected thousands of American children each year may be headed in the same direction.

A recent study my colleagues and I conducted using national electronic health record data found that hepatitis B vaccination rates among newborns declined by more than 10% between 2023 and August 2025.

At first glance, hepatitis B may seem like an unlikely threat to infants. The virus is spread through infected blood or bodily fluids, exposures that many parents assume newborns would rarely encounter. But before routine vaccinations began, hepatitis B infected about 18,000 children under the age of 10 in the United States each year.

About half of these infections were transmitted from mother to child during childbirth. The rest occurred through daily exposure within the household, often through contact with a caregiver or family member who did not know they were infected.

The consequences can last a lifetime. Although acute infection is often mild or asymptomatic, up to 90% of babies infected during their first year of life develop chronic hepatitis B. Over time, chronic infection can lead to cirrhosis, liver cancer, and liver failure.

The first major step towards prevention was screening. In 1988, universal screening for hepatitis B during pregnancy was recommended so that infants born to infected mothers could receive protection immediately after birth. The strategy identified many high-risk cases, but it did not prevent all infections. Each year, between 50 and 100 infants still developed hepatitis B.

To address these gaps, universal vaccination of newborns was recommended in 1991. Over the next decades, hepatitis B infections among children fell to fewer than 20 per year.

That’s why many doctors were surprised when in December the federal government’s Advisory Committee on Immunization Practices revised its recommendation for vaccinating newborns against hepatitis B. Under the new guidelines, babies born to mothers who test negative for hepatitis B can receive the vaccine based on an individual clinical decision rather than a universal recommendation.

The idea behind this approach is simple. If a mother tests negative, the immediate risk to the newborn is extremely low.

But the history of hepatitis B prevention shows why universal protection became necessary in the first place.

Today, an estimated 660,000 Americans are still living with chronic hepatitis B, and about half are unaware of their infection. The risks of exposure have not disappeared. They were controlled through vaccination and screening.

At the same time, national vaccine guidelines are becoming increasingly confusing. Earlier this year, the Centers for Disease Control and Prevention revised its childhood immunization schedule, moving several vaccines from universal recommendation status to topics of discussion for parents and health care providers.

The changes were not supported by new evidence. In response, the American Academy of Pediatrics created its own vaccination schedule that largely maintains previous recommendations.

Following a lawsuit against the CDC and the Department of Health and Human Services, a federal judge temporarily blocked changes to the federal recommendations and invalidated actions taken by the advisory committee.

The result is increasing confusion.

In my clinic, parents started asking questions I had never heard before. What vaccination schedule should we follow? Is this the schedule with all vaccines or just some of them? Vaccination decisions are influenced by science but also by trust and consistency. When parents receive mixed messages, some begin to question whether vaccines are really necessary. We have already seen the consequences of the decline in measles vaccination.

For decades, hepatitis B vaccination protected American children from a virus that once infected thousands each year. Because the disease has become rare, many parents and young doctors have never directly seen its consequences.

If measles is a warning, hepatitis B could be next.

The lesson of the past is simple. When we stop using effective vaccines, the diseases they prevent come back.

Joshua Rothman is a pediatrician at UC San Diego Health and clinical assistant professor of pediatrics at the UC San Diego School of Medicine.