Hepatitis B Vaccine: Schedule, Doses, and Boosters

The hepatitis B vaccine is given as either a 3-dose series (Engerix-B or Recombivax HB) at 0, 1, and 6 months, or a 2-dose series (Heplisav-B) with the two shots one month apart for adults 18 and older. A completed series protects more than 90% of healthy adults, and routine boosters aren't recommended MMWR, 2022.

Hepatitis B is a vaccine-preventable liver infection caused by the hepatitis B virus (HBV), spread mainly through blood, semen, and other body fluids: during sex, by sharing needles, or from a pregnant person to their baby at birth CDC. Vaccination is the single most effective way to prevent it, which is why ACIP now recommends it universally for adults aged 19–59 and for adults 60+ who have risk factors MMWR, 2024. This page covers the granular dosing questions the broader hepatitis vaccines overview doesn't fully resolve: exact schedules, what to do if you fall behind, and whether you ever need a titer or booster.

The 3-dose schedule: Engerix-B and Recombivax HB at 0, 1, and 6 months

Engerix-B and Recombivax HB are the older recombinant vaccines, and both follow the same three-dose timing. You get the first dose on day one, the second dose one month later, and the third dose about six months after the first. The series works by exposing your immune system to a surface protein of the virus (HBsAg) so your body builds antibodies without ever encountering live virus, there's no way to catch hepatitis B from the shot.

Rather than count the calendar out yourself, enter your first-dose date below and the scheduler returns the earliest date for each remaining dose, using the CDC minimum intervals, with a reminder you can save. Nothing you enter leaves your browser.

The intervals matter because each dose builds on the last. The minimum spacing between dose one and dose two is what drives early protection, while the final dose at the six-month mark is what locks in durable, long-lasting immunity. Giving the third dose too early can blunt the long-term antibody response, which is why clinicians hold to the six-month interval even when patients want to finish faster.

The 2-dose schedule: Heplisav-B, two doses one month apart

Heplisav-B is a newer adjuvanted vaccine approved for adults 18 and older, and its advantage is speed: just two doses given four weeks (one month) apart. For busy adults, that's a meaningful difference: you reach full coverage in about a month instead of half a year, with fewer clinic visits to remember.

Don't mix and match brands within a series if you can avoid it. If you started on a 3-dose product, the cleanest approach is to finish all three with that product; Heplisav-B's two-dose schedule only applies when both doses are Heplisav-B. When records are incomplete and brands are uncertain, your clinician will usually default to completing a full series rather than guessing.

The infant and birth-dose schedule, and why the first shot happens at birth

Every newborn should get the first hepatitis B vaccine dose within hours of birth, then complete the series over the following months. The reason is brutal arithmetic: age at infection decides the outcome. An adult who catches HBV clears it most of the time, fewer than 5% develop chronic infection CDC Pink Book. But an infant infected at birth has about a 90% chance of carrying the virus for life, and lifelong infection is what leads to cirrhosis and liver cancer CDC.

The most common way young children get hepatitis B is around the time of birth, which is why every pregnancy is screened for HBsAg. A baby born to an HBsAg-positive parent gets both the vaccine and hepatitis B immune globulin (HBIG, a dose of ready-made antibodies) within twelve hours of delivery, and the most common cause of perinatal infection is simply failing to give that immunoprophylaxis on time CDC. That combination drops transmission to roughly 3.6%, compared with 11.6% using vaccine alone network meta-analysis. For more on screening and prevention during pregnancy, see hepatitis and pregnancy.

What to do if you fall behind on doses

If you miss a dose or there's a long gap between shots, do not restart the series. The rule across all hepatitis B vaccines is simple: count the doses you've already had and continue where you left off, no matter how much time has passed. Your immune system retains the "memory" from earlier doses, so a delayed third shot still counts, restarting just means an extra needle for no benefit.

• Had one of three doses years ago? Get the second and third on the normal intervals from now.
• Had two of three and stopped? Just get the third, you don't need to repeat the first two.
• Lost track of how many you've had with no records? Your clinician may check a titer or simply give a full series, since extra doses are harmless.

Do you need a booster or a titer check?

For most healthy adults, the answer is no. A completed series produces protective antibody in more than 90% of immunocompetent people and gives long-lasting protection, so routine booster doses and routine titer checks aren't recommended for the general population. Antibody levels can fade over years, but immune memory persists and protects you even when a blood test no longer shows high circulating antibody.

Titer testing is reserved for specific situations: healthcare and lab workers with blood exposure, people on dialysis, those with weakened immune systems, and infants born to HBsAg-positive parents. In those groups a post-vaccination antibody test confirms the series worked, and people who don't respond may be revaccinated. If you have an immunocompromising condition, ask your clinician whether you fall into one of these exceptions.

How protection is confirmed: the anti-HBs test

Immunity from vaccination is measured with anti-HBs, antibodies to the surface protein. It's one piece of the triple serologic panel clinicians use to sort out hepatitis B status: HBsAg flags active infection, total anti-HBc indicates past or current infection, and anti-HBs signals immunity, whether from the vaccine or from recovering off an infection CDC. A vaccinated person shows anti-HBs positive but HBsAg and anti-HBc negative.

This distinction matters because the CDC now recommends screening all adults at least once in their lifetime, and pregnant people each pregnancy MMWR, 2023. That's a deliberate response to a hidden epidemic: more than half of people living with hepatitis B don't know they're infected, and 50%, 70% of acute cases cause no symptoms at all CDC. If you've had a possible exposure, the timing of testing matters, see when to test after exposure and get tested to know which window applies.

When to see a clinician

Get to care quickly if you've had a known exposure to someone who's HBsAg-positive: through sex, a needlestick, or shared injection equipment. Post-exposure prophylaxis is HBIG plus the vaccine, and it works best given as soon as possible, ideally within 24 hours. Don't wait to see if symptoms appear, because most people who develop acute infection feel nothing early on.

Also see a clinician if you're unsure of your vaccination history, you're pregnant, you're starting a job with blood exposure, or you're managing a chronic condition that weakens immunity. If you already know you carry the virus, chronic hepatitis B is controlled, not cured: antivirals like tenofovir or entecavir suppress it and lower liver-cancer risk, but they're usually taken for life AASLD, 2018. A diagnosis here is common, treatable, and handled by clinics every day; it says nothing about you as a person. To understand what an active infection can feel like, see hepatitis b symptoms.

Keep exploring on EasySTD: STD vaccines, STD incubation periods and Hepatitis B testing.