Viral Hepatitis Vaccination: Complete Schedules for Hep A and B Protection

Getting vaccinated against hepatitis A and B isn’t just about avoiding a bad case of the flu. It’s about protecting your liver-your body’s main detox center-from viruses that can cause lifelong damage, liver failure, or even cancer. The good news? These vaccines work incredibly well. The bad news? Many people don’t get them at all, or they get them wrong. If you’re trying to figure out when to get the shots, how many you need, or whether you should go with a combo vaccine, this guide cuts through the confusion with clear, up-to-date schedules based on the latest CDC and WHO guidelines.

Why Hepatitis A and B Vaccines Matter

Hepatitis A: The Food-and-Water Virus

Hepatitis A spreads through contaminated food or water, or close contact with someone who’s infected. You don’t need to travel overseas to catch it. Outbreaks happen in U.S. restaurants, daycare centers, and even among people who use drugs. The virus hits hard but usually doesn’t cause long-term liver damage. Still, it can land you in the hospital for weeks with jaundice, vomiting, and extreme fatigue. The vaccine prevents all of that.

Hepatitis B: The Silent Liver Killer

Hepatitis B is sneakier. It spreads through blood, sexual contact, or from mother to baby during birth. Many people don’t feel sick for years-even decades-while the virus quietly damages their liver. Over time, it can lead to cirrhosis, liver cancer, or death. The CDC estimates that 880,000 people in the U.S. live with chronic hepatitis B. The vaccine stops transmission before it starts. Since universal infant vaccination began in 1991, new infections in kids and teens have dropped by more than 95%.

Hepatitis B Vaccine Schedule: What You Need by Age

Infants and Children

For babies, the hepatitis B vaccine is a birthright. The first dose should be given within 24 hours of birth-if the baby is healthy and weighs at least 2,000 grams. This single shot cuts the risk of chronic infection by up to 90%. Delaying it even a few days increases the chance the baby will become a lifelong carrier.

The full series is three doses:

1. Birth (within 24 hours)
2. 1 to 2 months of age
3. 6 to 18 months of age

The final dose must be given after 24 weeks of age. Giving it too early won’t work. The CDC confirms this schedule gives 98-100% protection. Most pediatricians use Engerix-B or Recombivax HB, both single-antigen vaccines.

Adults (Ages 19-59)

In 2022, the CDC updated its recommendation: all adults aged 19 to 59 should get vaccinated, no matter their risk level. That’s a big shift from the old “only if you’re at risk” rule.

You have three options:

• Standard 3-dose schedule (Engerix-B or Recombivax HB): Doses at 0, 1, and 6 months. This is the most common and cheapest option. Protection lasts decades, possibly lifelong.
• Heplisav-B (2-dose): Doses at 0 and 1 month. It works faster and gives higher antibody levels-especially in older adults, diabetics, and people with weakened immune systems. But it has a black box warning for heart-related risks, so it’s not for everyone.
• PreHevbrio (3-dose): Newer option (approved in 2023). Same schedule as the standard, but uses a different technology. It’s just as effective and avoids the cardiac warning.

Adults 60+ and High-Risk Groups

For adults over 60, vaccination is still recommended-but only if your doctor says you’re at risk. Why? Studies show vaccine response drops after age 40. Only about 75% of people over 40 develop protective antibodies with the standard dose.

If you’re at high risk-such as having diabetes, kidney disease, HIV, or using injection drugs-you need higher doses or extra shots:

• People on hemodialysis: 4 doses of Engerix-B (2 mL each) at 0, 1, 2, and 6 months.
• Immunocompromised individuals: 3 doses of Recombivax HB (40 mcg/mL) at 0, 1, and 6 months.

Hepatitis A Vaccine Schedule: Simple but Precise

The hepatitis A vaccine is always given in two doses, at least six months apart. No shortcuts. No exceptions.

Children

Start between 12 and 23 months. That’s the sweet spot. Too early, and the immune system doesn’t respond well. Too late, and you miss the window for early protection.

• Dose 1: 12-23 months
• Dose 2: 6-18 months after the first (minimum 6 months apart)

Brands like Havrix and Vaqta are interchangeable. Either one works fine. The CDC doesn’t recommend a booster after the second dose-protection lasts at least 20 years.

Adults

Adults get the same two-dose schedule:

• Dose 1: Any time
• Dose 2: At least 6 months later

No need to start at a specific age. If you’re planning a trip to a country where hepatitis A is common-like Mexico, India, or parts of Eastern Europe-get the first dose at least 2 weeks before you leave. You’ll get some short-term protection even before the second shot.

Combination Vaccines: Twinrix and What It Means for You

Twinrix is the only vaccine that protects against both hepatitis A and B in one shot. It’s a game-changer for travelers, healthcare workers, and people who need both vaccines.

You have two schedules:

• Standard (3 doses): 0, 1, and 6 months. Same as getting the two vaccines separately.
• Accelerated (4 doses): 0, 7, and 21-30 days, then a booster at 12 months.

The accelerated schedule is perfect for last-minute travelers. By day 30, 94% of people have protective antibodies for both viruses. That’s way faster than waiting 6 months.

But here’s the catch: the fourth dose is mandatory. If you skip it, your long-term protection for hepatitis B may not last. One New York travel clinic found 12% of people never came back for the final shot.

Twinrix costs about $150-$180 per dose-nearly triple the price of standalone hepatitis B shots. Insurance often covers it for travelers or high-risk groups, but not always. Check with your provider.

What Happens If You Miss a Dose?

Don’t panic. You don’t have to start over.

Hepatitis B

If you miss the second dose, just get it as soon as you can. The third dose still needs to be at least 8 weeks after the second and 16 weeks after the first. The CDC says you can wait months-even years-to finish the series. The immune system remembers.

Hepatitis A

If you miss the second dose, wait at least 6 months after the first, then get it. No need to restart. Even if it’s been 2 years, the second shot still works.

Real-World Problems: Why People Don’t Get Fully Protected

The science is solid. The problem is execution.

• Babies miss the birth dose: In 2022, only 73% of U.S. newborns got the hepatitis B shot within 24 hours. Staffing shortages, especially overnight, are a major reason.
• Adults drop out: Only 33% of adults aged 19-49 completed the full hepatitis B series. The CDC says 41% of adults who start never finish. Scheduling conflicts, cost, and forgetfulness are the top reasons.
• Insurance denies coverage: One 45-year-old on HealthTap paid $450 out-of-pocket because their insurer refused to cover PreHevbrio, even though ACIP recommends it.
• Pharmacists are helping: In 22 states, pharmacists can now give hepatitis vaccines. Early data shows a 23% increase in adult vaccination rates when shots are available at pharmacies.

What’s Coming Next

The future of hepatitis vaccines is getting simpler.

• Valneva’s new HepA-HevB vaccine is in Phase 3 trials and could be approved by late 2024. It promises full protection with just two doses.
• The NIH is testing a single-dose hepatitis B vaccine using a new adjuvant. If it works, it could change everything.
• The WHO is already using fractional doses (one-fifth the normal amount) in low-income countries to stretch supplies. This could bring protection to millions who can’t afford full doses.

What to Do Now

If you’re reading this, here’s your action plan:

1. Check your records. Did you get the hepatitis B shot at birth? Did you finish the series as a kid? Did you get the hepatitis A shot as a child?
2. If you’re under 60: Get the hepatitis B vaccine. Choose Heplisav-B (2 doses) if you’re healthy and want speed. Choose PreHevbrio or the standard 3-dose if you have heart concerns.
3. If you’re over 60: Talk to your doctor. If you have diabetes, kidney disease, or liver disease, get vaccinated.
4. If you’re traveling: Get the first dose of hepatitis A at least 2 weeks before departure. Consider Twinrix if you’re going to a high-risk country.
5. Use your pharmacy. Most pharmacies offer both vaccines without a prescription. Walk in. Get it done.

Your liver doesn’t ask for much. Just one or two shots can keep it working for the rest of your life.