Basic overview of hepatitis A
Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus (HAV). It is primarily passed through ingestion of contaminated food or water or close personal contact with an infected person. Unlike hepatitis B or C, hepatitis A does not cause chronic liver disease and is rarely fatal, but it can cause debilitating illness and hospitalization. Recovery usually occurs within a few weeks to months.
There is an effective vaccine to prevent hepatitis A infection. Most hepatitis A vaccines only protect against hepatitis A. Separate vaccines exist for hepatitis B, and there is a combination vaccine for both hepatitis A and B. There is currently no vaccine for hepatitis C.
Impact on people who use drugs (PWUD)
- Higher risk of infection and severe illness
- Barriers to healthcare (e.g., unstable housing, stigma) may delay diagnosis and care
- HAV outbreaks among PWUD can rapidly spread without targeted vaccination efforts due to sharing or touching anything that could touch another person’s mouth (food, cigarettes, etc.)
Intersection with hepatitis C (HCV)
- Many PWUD are co-infected with hepatitis C
- HAV infection can cause severe liver damage or failure in those with existing HCV
- Vaccination is especially important for HCV-positive individuals
Transmission and prevention among PWUD
HAV is spread via the fecal-oral route. Among PWUD, the risk is higher due to:
- Close person-to-person contact in crowded or unsanitary conditions (e.g., encampments, shelters)
- Shared drug equipment
- Poor access to handwashing and other hygiene facilities
- Sexual activity, particularly among men who have sex with men
Prevention strategies include:
- Vaccination
- Promoting hand hygiene (handwashing with soap and water)
- Safer use practices such as not sharing drug equipment
- Sexual health education
- Improving access to clean living environments
Why Is the hepatitis A vaccine beneficial for PWUD?
- High Risk of Exposure: PWUD are disproportionately affected by HAV outbreaks
- Severe Outcomes: Co-infection with hepatitis C or other liver conditions increases the risk of liver damage or complications from HAV
- Preventable Illness: The vaccine is highly effective and safe, reducing risk of hospitalization, illness spread, and public health impact
- Outbreak Control: Vaccinating PWUD helps control and prevent community outbreaks, especially in unhoused or communal living environments
Recommendations
The CDC recommends hepatitis A vaccination for:
- All children aged 12–23 months
- Children and adolescents aged 2–18 years who have not previously been vaccinated
- Adults at increased risk, including:
- People who use drugs (injection and non-injection)
- People experiencing homelessness
- Individuals with chronic liver disease, hepatitis B/C, or HIV
- Men who have sex with men
- International travelers
Types of vaccines and differences
- Single-antigen Hepatitis A vaccine: Two doses, 6 months apart
- Combination Hepatitis A and B vaccine (Twinrix): Three doses over 6 months, approved for adults 18+. This vaccine should not be used for post-exposure prophylaxis.
Both types are safe, effective, and interchangeable if needed.
Vaccination schedule
| Age | Dose | Timing |
|---|---|---|
| Children (12-23 months) | Dose 1 Dose 2 | Between 12-23 months 6 months after first dose |
| Individuals (2 years and older) | Dose 1 Dose 2 | Any time after age 2 6 months after first dose |
| Combination A + B for Adults (Twinrix) | Dose 1 Dose 2 Dose 3 | Any time 1 month later 6 months after first dose |
You do not need to restart the series if doses were delayed—just complete the missing ones.
If vaccination history is unknown
- Check medical records if available.
- Serologic testing (anti-HAV antibodies) can confirm immunity. (Providers should order total antibody when testing for immunity; IgM specifically should only be ordered if acute infection is suspected.)
- When in doubt, vaccinate. There’s no harm in receiving the vaccine again if the person was already immune.
- If only the first dose was received, complete the series—no need to restart.
Vaccine effectiveness and duration of protection
- Over 95% effectiveness after the full series
- Protection begins about 2 weeks after the first dose
- Long-term protection lasts at least 20 years, likely lifelong
Vaccination in pregnancy and lactation
- Hepatitis A vaccine is safe during pregnancy and breastfeeding
- Recommended if there is increased risk of HAV exposure (e.g., due to drug use or travel)
Post-exposure prophylaxis (PEP)
Unvaccinated individuals exposed to HAV should receive:
- Hepatitis A vaccine (single antigen) within 2 weeks of exposure
- Immune globulin (IG) may be recommended in addition to vaccine for those over 40, those with immunocompromising conditions or chronic liver disease, or infants under 12 months
For long term immunity, the hepatitis A vaccine series should be completed with a second dose. However, the second dose is not necessary for PEP; a single dose is highly effective.
Treatment for hepatitis A
There is no specific antiviral treatment for HAV. Management of symptoms can be addressed through:
- Rest, hydration, and nutrition
- Monitoring for complications, especially in those with pre-existing liver disease