The Twinrix vaccine is a combined shot that protects against both hepatitis A and hepatitis B in one series. Adults usually get three doses on a 0/1/6-month schedule, or an accelerated 0/7/21-day course with a booster about a year later. It's the most reliable way to prevent both liver infections at once.
Key figures
- Protects against
- Hep A + B
- combined inactivated HAV + recombinant HBsAg
- Standard schedule
- 3 doses
- 0, 1, and 6 months
- Accelerated option
- 0·7·21–30 d
- + booster at 12 months, for time-sensitive travel
- For
- adults 18+
- who need protection from both A and B
| Item | Value |
|---|---|
| Protects against | Hep A + B: combined inactivated HAV + recombinant HBsAg |
| Standard schedule | 3 doses: 0, 1, and 6 months |
| Accelerated option | 0·7·21–30 d: + booster at 12 months, for time-sensitive travel |
| For | adults 18+: who need protection from both A and B |
Why combine hepatitis A and B in one vaccine?
Hepatitis A and hepatitis B are different viruses that both attack the liver, and Twinrix bundles protection against both into a single injection series. The two infections often share the same risk groups, travelers, men who have sex with men, people who use drugs, so covering both at once means fewer clinic visits and fewer needles for the same protection. If you want a side-by-side on how these viruses differ, see our breakdown of hepatitis a vs b vs c.
Hepatitis A is a viral liver infection caused by the hepatitis A virus (HAV) CDC. Unlike hepatitis B and C, it does not cause chronic infection, people recover completely. Hepatitis B behaves differently. It can become a long-term infection that quietly damages the liver over years, so a vaccine that heads it off early carries weight.
How well the vaccine protects, and the alternatives
Vaccination is the foundation. For hepatitis A, the CDC says vaccination is the best way to prevent it CDC; good hand hygiene also helps limit spread but doesn't replace the shot. For hepatitis B, the vaccine is the single most effective tool. Twinrix delivers both.
- Get vaccinated. The combined series produces protective immunity against both viruses; the standalone hepatitis a vaccine is an alternative if you only need hepatitis A coverage.
- Practice good hand hygiene. Washing thoroughly after using the bathroom and before handling food cuts the fecal-oral spread that drives hepatitis A.
- Use barriers during sex. Condoms and dental dams lower the risk of the sexually transmitted routes, especially oral-anal contact.
- Be careful with food and water when traveling. Hepatitis A spreads through contaminated food or water, a real concern in places with poor sanitation.
Who should get the Twinrix vaccine?
Twinrix is for adults who want or need protection against both viruses. Hepatitis A spreads by the fecal-oral route: swallowing the virus, even in tiny amounts, through contaminated food or water or close personal contact. Sexual transmission happens too, particularly through oral-anal contact, and outbreaks have occurred among men who have sex with men, people who use drugs, and people experiencing homelessness ACIP. Anyone in those groups, plus international travelers and people with chronic liver disease, has a clear reason to be covered for both infections.
The Twinrix schedule: standard vs. accelerated
There are two ways to complete the series, and the right one depends on your timeline. The standard schedule spreads doses over months for steady, durable protection. The accelerated schedule compresses the first three doses into a few weeks if you're traveling soon, but it requires a booster roughly a year later to lock in long-term immunity.
| Schedule | Doses | Timing | Best for |
|---|---|---|---|
| Standard | Three doses | 0, 1, and 6 months | Most adults planning ahead |
| Accelerated | Three doses plus a booster | Days 0, 7, and 21, then a booster about a year later | Travelers or anyone needing fast coverage |
A practical note from how clinics run this: complete the full series. People sometimes get the first dose before a trip and never come back, which leaves protection incomplete. Set a reminder for each follow-up dose, especially the year-out booster on the accelerated track, which is the one most often forgotten.
Putting it together
For full coverage against both viruses: complete the Twinrix series, use condoms during sex to cut the transmissible routes, wash your hands well around food and the bathroom, and keep routine testing in your rotation. Reported acute hepatitis A collapsed from nearly 10,000 cases in 2020 to about 1,600 in 2023 as the large person-to-person outbreaks waned CDC, 2023, and vaccination is a big part of why those outbreaks fade. If you do end up with a diagnosis, it's common and treatable; clinics handle it daily.
When to see a clinician
See a clinician to start or finish the Twinrix series, especially before international travel or if you fall into a higher-risk group. Also seek care if you develop signs of acute hepatitis, yellowing of the skin or eyes (jaundice), dark urine, pale stools, deep fatigue, nausea, or pain under the right ribs, since a blood test can confirm what's going on. If you've had a recent exposure and aren't vaccinated, ask promptly, because timing affects your options.
Keep exploring on EasySTD: STD vaccines, when to re-test and Hepatitis A testing.