You're booking a trip, starting a new job in food service, or your child is due for shots, and someone mentions the hepatitis A vaccine. You're not sure if you need it, how many shots it takes, or whether it actually works. Good news: this is one of the most reliable vaccines we have, and the schedule is simpler than you might think.
Hepatitis A is a liver infection caused by a virus that spreads through contaminated food and water. The vaccine prevents it, and the protection is long-lasting. Here's what to know before your appointment.
What is the hepatitis A vaccine, and how does it work?
The hepatitis A vaccine protects you from hepatitis A virus (HAV), which infects the liver. The vaccine teaches your immune system to recognize and fight the virus before it can make you sick, so if you're later exposed, your body already knows how to respond.
Hepatitis A spreads mainly through the fecal-oral route, meaning the virus travels from an infected person's stool into another person's mouth, usually through contaminated food or water, poor sanitation, or close contact. Young children are often infected without any symptoms, while symptomatic illness is more common in adults. That's part of why vaccination matters: a person can spread the virus without feeling sick.
Most hepatitis A vaccines used worldwide are inactivated, meaning they contain a killed version of the virus that cannot give you the infection. Inactivated hepatitis A vaccines were first licensed in 1992, so they have a long track record.
How many doses do you need, and what's the schedule?
The number of doses depends on which vaccine you receive. There are two main options in the U.S.: a single-antigen hepatitis A vaccine and a combination vaccine that protects against both hepatitis A and hepatitis B.
Here is how each schedule works, according to the CDC and ACIP:
- Single-antigen hepatitis A vaccine: 2 doses given 6 months apart. Havrix is given 6 to 12 months apart; Vaqta is given 6 to 18 months apart, with a minimum interval of 6 months between doses.
- Combination HepA-HepB vaccine (Twinrix): 3 doses given at 0, 1, and 6 months. An accelerated schedule of 0, 7, and 21 to 30 days plus a booster at 12 months is available for travelers.
- Both schedules complete protection over about 6 months, so it's worth starting early if you have a trip or deadline coming up.
Who should get the hepatitis A vaccine?
The vaccine is recommended for both routine childhood immunization and for adults at increased risk. ACIP recommends routine hepatitis A vaccination for all children at ages 12 to 23 months, with catch-up vaccination for unvaccinated children and adolescents ages 2 to 18.
For adults, vaccination is recommended for anyone who is unvaccinated and at increased risk of infection or of severe disease. Talk to a clinician about whether you fall into a higher-risk group, which commonly includes international travelers and people with certain health or exposure factors.
Hepatitis A still causes serious illness around the world. The World Health Organization estimates that in 2023, about 35,569 people died from hepatitis A worldwide. Because the virus spreads easily and can cause severe disease, broad vaccination is encouraged.
How long does the hepatitis A vaccine last?
Protection from the hepatitis A vaccine is long-lasting. In studies of people who completed the full vaccine series, anti-HAV antibodies have been shown to persist for at least 20 years.
Long-term follow-up studies and mathematical models go further, predicting protection lasting 25 years or more after primary vaccination, and the immune system appears to retain a memory response even when measured antibody levels fall. Because of this durability, no booster is currently recommended for people who have completed the series.
What if you've already been exposed to hepatitis A?
If you think you've been exposed, timing matters. The hepatitis A vaccine can be used for postexposure prophylaxis, meaning it can still prevent infection if given soon enough after contact with the virus.
According to the CDC, the vaccine effectively prevents infection when administered within 2 weeks (14 days) of exposure, for all people aged 12 months and older. In some cases, a clinician may also recommend immune globulin alongside or instead of the vaccine, depending on your age and risk. The effectiveness of the vaccine given more than 2 weeks after exposure is not established, so reach out to a clinician quickly if you've been exposed.
When to see a doctor
See a healthcare provider to get vaccinated before international travel, before starting a job or activity that raises your risk, or if you're simply not sure whether you've ever had the vaccine. A clinician can check your records and recommend the right schedule.
Get prompt medical care if you've been exposed to hepatitis A, especially within the past 2 weeks, since early treatment can prevent illness. Also seek care if you develop signs of hepatitis such as yellowing of the skin or eyes, dark urine, severe fatigue, nausea, or abdominal pain. Go to the emergency room or seek urgent care if you have severe abdominal pain, persistent vomiting, confusion, or marked yellowing of the skin or eyes. This article is general education, not personal medical advice, so your own clinician should guide your vaccine and treatment decisions.
Medical Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before starting any new skincare treatment, especially if you have underlying health conditions, are pregnant, or are taking medications.
