Hepatitis B vaccination: Are parents making an informed decision?

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A choice made within the first day of life can have effects that remain hidden for many years. New research indicates that moving away from universal hepatitis B vaccination at birth might lead to only a modest rise in childhood infections, while leaving far more young adults exposed to a disease that can last a lifetime. If vaccination becomes a shared decision, what should parents know in order to make that decision on equal footing with their physician?

A silent infection with lasting consequences

About two million Americans are living with chronic hepatitis B virus (HBV) infection, which has no cure. Without treatment, 25% of infected people may develop serious complications such as cirrhosis and liver cancer. Because HBV is usually detected through abnormal lab results rather than symptoms, people often learn about it only after seeing a physician.

HBV spreads through contact with infected blood and other body fluids, including transmission between adults and children in homes and communities. Of particular concern is passage from mother to infant during pregnancy or delivery, since 90% of newborns infected around birth and lacking immune protection go on to develop chronic HBV infection.

Building layers of protection

Universal screening in pregnancy began in 1988, followed by giving hepatitis B immune globulin to at-risk newborns, universal infant vaccination in 1991, and a stronger recommendation in 2018 that babies receive the first dose within 24 hours of birth.

This layered approach reflects the “Swiss Cheese” model of protection: every preventive measure has gaps, and multiple layers help cover one another. With that strategy in place, perinatal and early-childhood HBV infections fell from more than 25,000 a year in 1985 to fewer than 100 reported cases in 2024.

When universal protection becomes an individual choice

Federal vaccine advisers later recommended replacing universal hepatitis B vaccination at birth with individualized decision-making for infants whose mothers tested negative. A subsequent federal revision moved further toward risk-based and shared clinical decision-making. A federal court later stayed those changes, leaving the earlier universal birth-dose recommendation in effect. Even so, the proposed shift raises a key question: what would happen if vaccination were no longer routine but instead depended on individual assessment?

In a system where shared clinical decision-making could be translated as making your own disease trajectory, informed choice matters greatly. A new study provides data for families considering that path.

Three strategies, three possible futures

The study, published in Annals of Internal Medicine, modeled three prevention strategies using disease-trajectory data. It followed a hypothetical group of 3.6 million U.S. children from birth to age 20. The main outcomes were the number developing chronic hepatitis B and the number reaching adulthood susceptible to infection. It is worth noting that the study is a model, so its conclusions depend on assumptions about vaccine uptake and transmission risk.

The three strategies were:

• Universal birth-dose vaccination: the earlier recommendation that every newborn receive the first hepatitis B vaccine dose within 24 hours of birth, regardless of maternal infection status. The model assumed 91.1% would complete the series by 24 months.

• Deferred vaccination: part of the newer recommendation in which infants start the vaccine series at 2 months rather than at birth, delaying protection. The model assumed 87.1% completion.

• Shared decision-making: the other part of the newer recommendation, in which vaccination is no longer universally recommended and instead depends on parent-clinician discussion or identification of higher risk. The model assumed only 50% would complete vaccination. In all three strategies, birth vaccination still remained recommended for infants whose mothers had hepatitis B or whose status was unknown.

Small numbers, large consequences

Under the older universal birth-dose strategy, the model projects 255 chronic HBV infections among the 3.6 million children tracked through age 20. Delaying vaccination until 2 months raises that number to 303, while shared decision-making increases it to 467. The more dramatic difference appears in the number of young adults still susceptible to infection: 232,000 under universal birth-dose vaccination, 474,000 with delayed vaccination, and 1.8 million with shared decision-making.

Horizontal infections are those acquired from another household member, or from the mother after the perinatal period. In every strategy, because children at highest risk remain protected, infections among infants born to known HBV-infected mothers stay essentially unchanged. The increases come from horizontal transmission and from children who are never vaccinated at all.

Although the number of infections remains small — less than 0.05% of the full 3.6 million cohort — susceptibility steadily rises under each strategy until it reaches just over 50% of the group. Susceptibility is not the same as infection, but a larger unprotected population can fuel adult HBV cases later on. The overall message is that the newer recommendations produce only a modest absolute increase in infections, but the long-term effects may be much larger than they first appear.

What happens when the assumptions change?

Additional scenarios examined what might happen if vaccine completion or newborn vaccination rates fall, if maternal prevalence and horizontal exposure risk rise, and if vaccination is deferred for the first two months of life.

The study’s most important public health insight may be the gap between the relatively small increase in childhood infections and the much larger number of people entering adulthood without protection.

The extra data also highlights two main drivers of infection in the model. Delaying vaccination increases risk in two ways: children remain exposed for longer to household and community transmission, and later vaccination also makes completion of the three-dose series less likely, leaving more people susceptible as adults.

Second, when declining vaccination extends to infants whose mothers are infected or whose infection status is unknown, the model projects nearly three times as many birth-acquired infections as with universal birth-dose vaccination. The key difference is that delaying vaccination mainly extends the period without protection, while replacing universal vaccination with shared decision-making may leave many children unvaccinated altogether.

The results, especially those tied to shared decision-making, depend heavily on assumptions. The investigators estimated that vaccine completion would fall to 50% because outcomes are too early to measure after implementation. They also assumed that the monthly chance of horizontal HBV exposure varied by age, ranging from 25 to 300 exposures per 100,000 people per month. Much of the projected rise in susceptibility flows from those assumptions.

Two other studies support the general direction of the findings, even if they do not fully reproduce the model’s exact numbers.

Does missing the first dose mean missing the rest?

A retrospective study in JAMA Network Open examined more than one million children in the Vaccine Safety Datalink, which contains electronic health records from nine geographically distinct sites. Researchers focused on children who received the hepatitis B vaccine and divided them into two groups based on whether they got the vaccine within three days of birth. The outcome was completion of the full three-dose series by 18 months.

Among children who received a birth dose, 97% completed the full series by 18 months and were therefore the most fully protected. Among those who did not receive a birth dose, only 67.5% completed the series by 18 months, and slightly more than a quarter received no vaccination at all. The study covered results from 2014 through 2023. While full vaccination in the birth-dose group stayed steady, completion declined in the delayed-dose group, with only 55% of the 2023 cohort fully immunized by 18 months.

In practice, the link between the birth dose and series completion is substantial, and delaying vaccination increased incomplete vaccination even before the new guidelines were proposed. The JAMA findings support the model’s estimate for birth-dose recipients and suggest the model may have been too optimistic about deferred vaccination, since it assumed 87% completion while the real-world rate was 67.5%. At the same time, the 55% completion rate among the delayed-vaccination 2023 cohort offers some support for the model’s 50% assumption.

Overall, the JAMA study strengthens the model’s direction while leaving uncertainty about the size of the effect.

Risks beyond the birth mother

One of the model’s most notable findings is the importance of horizontal transmission. Under universal birth-dose vaccination, about 12% of projected chronic childhood infections come from horizontal spread. With shared decision-making, that share rises to about 50%. In absolute terms, the model projects nearly eight times as many horizontally acquired chronic infections under shared decision-making as under universal birth-dose vaccination.

The researchers openly note that horizontal transmission is one of the model’s biggest uncertainties. For real-world evidence, the article points to an abstract from a recent infectious disease conference by Kaiser Permanente’s research division. That data came from a retrospective review of health records that identified diagnoses of horizontal sources within a household, not measured transmission.

Kaiser found that about 1,280 per 100,000 children were living with an infected household member at any one time. Household prevalence is not the same as exposure events, but the figures suggest that the model’s horizontal exposure estimate of 25 to 300 per 100,000 children is biologically plausible. The findings also support the idea that hepatitis B prevention cannot rely solely on identifying infected mothers.

What about vaccine risks?

The CDC lists soreness at the injection site, fatigue, and fever as recognized side effects. Serious allergic reactions are rare, and safety monitoring has not found unexpected major concerns. A 2026 review in Pediatrics found strong evidence that birth-dose vaccination is safe and effective, with no proven safety advantage to delaying it.

An informed choice requires more than permission to choose

Informed consent means more than simply asking parents whether they want their newborn vaccinated. It means giving them the information they need to weigh benefits, risks, and uncertainties. For hepatitis B, the immediate risk for most newborns is low, especially when the mother has tested negative. The vaccine has a long record of safety and effectiveness, though, like any medical intervention, it is not completely risk-free. What is harder to predict is a child’s exposure to hepatitis B over the decades ahead, or whether postponing the first dose will mean never finishing the series.

Parents should be able to ask questions, challenge recommendations, and take part in decisions that affect their children. But choice without understanding the consequences is not truly informed consent. If parents are expected to make these decisions, they deserve more than reassurance or slogans. They deserve the evidence, including what is known, what remains uncertain, and what their children may ultimately live with.

[1] The model included five possible disease states: newborn, susceptible to hepatitis B, immune through vaccination, recovered from a previous infection, and chronically infected; as well as perinatal transmission from mother to infant around birth and horizontal transmission through later household or community exposure.

Source: Projected Effect of 2026 Federal Changes to the Childhood Immunization Schedule on Chronic Hepatitis B Virus Infections in the United States Annals of Internal Medicine DOI: 10.7326/ANNALS-26-02135

Hepatitis B Vaccine Series Completion by 18 Months in Infants Without a Birth Dose JAMA Network Open DOI: 10.1001/jamanetworkopen.2026.9962