Hepatitis B is sexually transmissible and 100x more infectious than HIV. The vaccine works — here's the schedule and what to do if you've fallen behind.

Hepatitis B Vaccine — Schedule, Doses, Immunity

Hepatitis B is the only STI we have a really effective vaccine for that isn't HPV. It's also one of the most infectious — about 100 times more infectious than HIV per exposure. The vaccine is highly effective (95%+ in healthy adults) and protection lasts for decades, possibly lifelong, for most people.

Here's the current 2026 adult schedule, what to do if you missed doses, and when (if ever) you'd need a booster.

The short answer

Two vaccine formulations are commonly used in US adults:

Heplisav-B (preferred for adults)

2 doses, 1 month apart
95%+ seroconversion in healthy adults
FDA-approved for adults 18+
Adjuvant: CpG 1018 (newer, stronger immune response)

Engerix-B / Recombivax HB (3-dose series)

3 doses at 0, 1, and 6 months
90-95% seroconversion in healthy adults
The older standard
Still used widely

After completing either series, most people develop long-lasting immunity. Routine boosters are NOT recommended for healthy adults.

Who should get vaccinated

CDC's 2022 recommendation: all adults aged 19-59 should be vaccinated. Adults 60+ should be vaccinated if they have risk factors.

Always vaccinate

Anyone aged 19-59 (universal)
Healthcare workers
People with multiple sexual partners
MSM (men who have sex with men)
Sex workers
People who inject drugs
Household contacts of someone with hepatitis B
People with HIV
People with chronic liver disease
People with hepatitis C
Patients with diabetes (especially in nursing homes)
People on dialysis
Pregnant women without prior vaccination or immunity

Vaccinate adults 60+ with risk factors

Risk factors: sexual exposure, IV drug use, household contact with HBV, healthcare work, chronic liver disease.

Not currently recommended

Routine booster doses in immunocompetent adults who completed the series.

The Heplisav-B 2-dose schedule

Dose 1: at day 0
Dose 2: at 1 month (~28 days later)
Both doses are intramuscular (deltoid)
Most adults seroconvert (have detectable anti-HBs antibody) within 1-2 months of dose 2

The Engerix-B / Recombivax HB 3-dose schedule

Dose 1: at day 0
Dose 2: at 1 month
Dose 3: at 6 months
Intramuscular (deltoid)

Acceptable spacing: at least 4 weeks between doses 1 and 2, at least 8 weeks between doses 2 and 3, and at least 16 weeks between doses 1 and 3.

What if I missed a dose?

You don't restart the series. Continue from where you left off.

Missed second dose by months or years? Just get it now.
Missed third dose (older series)? Just get it now.
Started one brand, switching to another? Fine — finish with either.

The immune system "remembers" the first dose for years to decades.

How to know if you're immune

A blood test called anti-HBs (hepatitis B surface antibody) measures your protection level.

Anti-HBs ≥ 10 mIU/mL: Protected
Anti-HBs < 10 mIU/mL: Not protected; needs revaccination

When to test post-vaccination:

Routinely: Not necessary for healthy adults
Required: Healthcare workers, dialysis patients, infants of HBV+ mothers, immunocompromised people, exposure follow-up

Antibody levels can fall over time, but immune memory persists. Studies show 20+ years of protection even when anti-HBs is no longer detectable — the immune system mounts a response on re-exposure.

What if I'm not immune after the full series?

About 5-10% of people don't seroconvert after a complete series. Options:

Get a second full series

Especially using the alternative formulation (e.g., switch to Heplisav-B if you didn't respond to Engerix-B)
50-75% of "non-responders" seroconvert after second series

High-dose recombinant vaccine

40 mcg formulations exist for dialysis patients and severe non-responders
Limited availability

Reasons for non-response

Older age
Obesity
Smoking
Immunosuppression (HIV, chemotherapy, dialysis)
Genetic factors

Talk to your provider about the right next step.

What is hepatitis B and why does it matter?

Hepatitis B is a viral infection of the liver that can be:

Acute — short illness with jaundice, fatigue, nausea (sometimes asymptomatic)
Chronic — long-term infection that can cause cirrhosis, liver failure, liver cancer

Transmission

Blood and body fluid contact (sex, needles, mother-to-baby)
Sharing toothbrushes, razors that have blood
Sexual transmission — about 25-50% transmission per partner per year in unvaccinated couples

Chronic HBV risk

Newborns who get HBV: 90% become chronic
Children 1-5 years: ~25-50%
Adults: ~5% become chronic
Most chronic HBV in the US is among immigrants from high-prevalence countries

How dangerous is it?

About 850,000 to 2.4 million Americans have chronic HBV
Up to 25% of those eventually die of HBV-related liver disease
Liver cancer is one of the most lethal common cancers

The vaccine is one of the highest-impact preventive interventions available.

What if I've already been exposed?

Hepatitis B has a known post-exposure prophylaxis (PEP):

After known HBV exposure

HBIG (hepatitis B immune globulin) plus HBV vaccine within 24 hours (ideally), up to 7 days for sexual exposure, up to 14 days for needle exposure
Complete the vaccine series

Newborns of HBV+ mothers

HBIG + first vaccine dose within 12 hours of birth
Complete vaccine series per schedule
This combination is 95%+ effective

Side effects

The vaccine is well-tolerated. Common side effects:

Injection-site soreness or redness
Mild fatigue or headache for 1-2 days
Low-grade fever (uncommon)
Allergic reactions are very rare

Heplisav-B can have slightly more local reactions but similar overall tolerability to older vaccines.

Special situations

Pregnancy

Hepatitis B vaccine is safe in pregnancy (inactivated, non-replicating)
Recommended for any pregnant woman at risk who isn't already immune
All pregnant women in the US are screened for HBsAg

Immunocompromised

HIV+, dialysis, post-transplant — vaccine works less well
May need higher doses or more frequent boosters
Antibody testing post-vaccination is recommended

Travel

Recommended for travel to countries with high HBV prevalence (East/Southeast Asia, sub-Saharan Africa, Pacific Islands)
Combination Twinrix (hep A + hep B) is convenient for travelers

Combo vaccines

Twinrix (hep A + hep B): 3 doses at 0, 1, 6 months
Pediarix and others contain HBV for childhood schedule

Cost and access

Heplisav-B and Engerix-B/Recombivax HB are covered by most insurance under preventive services (no co-pay for adults under 60)
Without insurance: $35-150 per dose at retail pharmacies
Health departments offer free or low-cost vaccination
Many sexual-health clinics provide it free

What this means for STI prevention

Hepatitis B is the most-vaccinatable STI. It's underrated because:

Most people don't think of it as an STI
The vaccine is so effective it's become invisible (people forget how serious it was)
Childhood vaccination has driven down rates

If you're a sexually active adult and don't know your vaccination status — find out. Antibody testing is cheap. Vaccination is cheap. The downside of chronic HBV is enormous.

What to do today

Ask your provider: "Am I vaccinated against hepatitis B? What's my anti-HBs level?"
If unsure: get an anti-HBs test (~$15-50 if cash)
If unvaccinated: start the series — 2 doses (Heplisav-B) or 3 doses (Engerix-B)
If incomplete: finish from where you left off
If non-responder: discuss revaccination strategy

Bottom line

The hepatitis B vaccine is:

95%+ effective
2 doses with Heplisav-B (preferred) or 3 doses with Engerix-B/Recombivax HB
Boosters not needed for healthy adults who completed the series
Universal recommendation for adults 19-59
Covered by most insurance with no co-pay

If you're an adult and don't know your status, find out. The downside of not knowing is real. The cost of getting protected is trivial.

For more on STI prevention, see our PrEP vs PEP guide, HPV vaccine for adults over 26, and do condoms prevent STIs?.