Hepatitis D Vaccine Safety, Changing Guidance, and the Pharmacist’s Role

In a conversation with Pharmacy Times, immunologist Morgan McSweeney, PhD, outlines what decades of evidence show about the hepatitis B vaccine’s safety profile in infants, emphasizing its extraordinarily strong performance even among vaccines held to high safety standards. He explains how conflicting messages from federal agencies, medical organizations, and social media can create confusion for parents and highlights the unique position pharmacists hold in building trusted relationships, identifying risk factors, reducing barriers to vaccination, and countering misinformation with clear, accessible science.

Q: What does the evidence show about the safety profile of the hepatitis B vaccine in infants, and how should pharmacists communicate this to concerned parents?
Morgan McSweeney, PhD: I understand why a lot of people aren’t quite sure what to believe about the hepatitis B vaccine or vaccines in general. At this point, we’re hearing conflicting messages from the Secretary of Health and Human Services, from the CDC itself—which may be at odds with your own pediatrician, or the American Academy of Pediatrics, or the American Academy of Immunologists, or the American Medical Association, or you can put every other professional medical organization on the other side of that argument. And then the third side, of course, is what you’re seeing on social media from people like me who claim to have credentials and present evidence or published papers in a very convincing manner, saying something that agrees with either your pediatrician or the CDC or whatever it might be. It’s very confusing.

But the hepatitis B vaccine actually has, even among vaccines—which have a high standard for safety—a phenomenal safety profile. Vaccines in general are held to a higher standard of safety because you're giving them to usually otherwise healthy children. It’s very different from treatments like cancer treatments, where you’re willing to accept a serious burden of risk from the drug itself because of the severity of the cancer. That benefit–risk ratio changes quite a bit for vaccines.

The bar for safety is extremely high, and even in that context, the hepatitis B vaccine is extraordinarily safe relative to other vaccines. There was a big review conducted recently out of SIDRAP, looking at hundreds of studies over 40 years of data on both short-term and long-term potential adverse effects. They found no signal for anything in the long term—things like autoimmune disease, allergies, neurologic manifestations, Autism Spectrum Disorder. No signal for any of that. In the short term, there’s fever, local reactogenicity, and some fussiness after vaccination—nothing serious.

The safety profile is astonishingly good, even among vaccines. And that’s part of what justifies universal vaccination. Some infants are at much lower risk of hepatitis B transmission—maybe their mother had a negative test result, maybe they won’t be in daycare and will be at home in a bubble. Even among those children, the vaccine safety profile is so good that the recommendation is: get it anyway. You’ll be protected against potential unknown exposures.

Unknown exposures do happen because about 50% of people with hepatitis B are unaware. You may think your baby isn't at risk, even at home, but even if the mother has a negative test result, the father may be positive, grandparents may be positive, children may be positive, or they may pick it up from others at daycare. It’s hard to know for sure, but since the vaccine is so safe, that benefit–risk ratio supports the recommendation that all children should receive it.

Q: Given the changing national guidance, how should pharmacists play a role in maintaining protective vaccination rates and identifying patients who may be newly at risk for hepatitis B exposure?
McSweeney: I think pharmacists sit in an important spot that immunologists don’t, that people on the purely research side don’t, and that public health officials don’t. The AAP doesn’t. Pediatricians kind of do. Pharmacists can build a personal relationship with people in a way that builds trust. They see you’re not some faceless arm of the pharmaceutical industry.

So pharmacists have an opportunity to build rapport and then work into the discussion the identification of risk factors, and communicate in an authentic way what their experience is with managing or seeing patients with liver disease or liver cancer—what the consequences are of an unseen infection that could happen 30 years later.

A lot of people don’t know much about hepatitis B beyond what they see on social media. So it’s a good opportunity to quickly assess what people know, see gaps in their vaccination record, and offer solutions. Anything you can do to reduce barriers—same-day vaccination rather than “come back in two weeks if you can find a slot”—helps reduce friction and helps people make choices they may already want to make but have found difficult or expensive. Pharmacists sit in a good position to help resolve those issues.

Q: How do changes (or attempted changes) to federal immunization recommendations impact vaccine confidence, and what strategies can pharmacists use to counter misinformation with clear, accessible science?
McSweeney: I think the current Health and Human Services is only causing confusion. They’re causing distrust of scientific and medical bodies without offering much of a solution. I’m not sure how many people actually read the CDC webpage, or how many people watch the ACIP vaccine committee panel recommendations—it’s a vanishingly small number.

The negative effects are downstream. Influencers take clips from these meetings—now in a very official context with the CDC logo—and they get millions of views on Instagram or TikTok. That’s where inadequate presentations of evidence start affecting vaccine confidence.

It used to be simple to tell people, “If you’re not sure what to believe, go look at the CDC website.” Scientists who spent decades on this put together rigorous evidence-based information. Now we’re seeing that’s not necessarily the case, with entire CDC pages being updated without consulting CDC scientists, sometimes promoting vaccine conspiracy theories without solid evidence. It’s confusing.

At the end of the day, people are best served by talking to their own pediatrician, pharmacist, or health care provider about decisions for themselves and their families. The American Academy of Pediatrics and the American Medical Association are doing a good job stepping up to resolve some of this confusion, but it’s an unfortunate circumstance where we have warring medical bodies, and it’s hard to know who to believe.