Do people with prior Hepatitis A (HAV) infection need to get immunized against Hepatitis A?

Hepatitis A Vaccination After Prior Infection

People with prior HAV infection do not need to get immunized against Hepatitis A as they already have lifelong immunity from their previous infection. 1

Understanding Hepatitis A Immunity

Hepatitis A infection results in lifelong immunity through the production of antibodies. When someone recovers from a HAV infection, they develop:

• IgG antibodies against hepatitis A virus (anti-HAV IgG) that persist for life
• Complete protection against future HAV infections 1

This natural immunity is equivalent to the protection provided by vaccination, making additional vaccination unnecessary for those with prior infection.

Serologic Testing for HAV Immunity

When to Consider Testing Before Vaccination

Prevaccination testing may be cost-effective in certain populations with high rates of previous HAV infection:

• Adults born in or who lived extensively in areas with high/intermediate HAV endemicity
• Older adolescents and adults in certain population groups (American Indians, Alaska Natives, Hispanics)
• Adults in high-prevalence groups (e.g., injection drug users)
• Adults over 40 years (overall anti-HAV prevalence >33%) 2

Testing is generally cost-effective when:

• The cost of screening is approximately one-third the cost of the vaccine series
• The prevalence of prior infection in the population is >33% 2

Appropriate Testing Methods

• Total anti-HAV antibody test: Appropriate for screening for immunity
• IgG anti-HAV test: Indicates lifetime immunity from either past infection or vaccination
• IgM anti-HAV test: Only appropriate for diagnosing acute infection (not for immunity screening) 1

Special Considerations

High-Risk Groups

While those with prior HAV infection don't need vaccination, certain groups without prior infection should be prioritized for vaccination:

• Persons with chronic liver disease are at increased risk for severe complications if infected with HAV 3
• The Advisory Committee on Immunization Practices (ACIP) recommends vaccination for persons with chronic liver disease due to the higher fatality rate associated with HAV superinfection 3

Post-Exposure Scenarios

For individuals with documented prior HAV infection who are exposed to the virus:

• No post-exposure prophylaxis is needed as they already have protective antibodies 1
• This differs from recommendations for susceptible individuals, who would require either hepatitis A vaccine or immune globulin depending on age and health status 2

Practical Application

1. For known prior HAV infection: No vaccination needed
2. For unknown status in high-risk groups: Consider serologic testing before vaccination
3. For general population: Routine testing before vaccination is not indicated for children due to their expected low prevalence of infection 2

Common Pitfalls to Avoid

• Don't confuse acute and past infection markers: IgM antibodies indicate recent infection while IgG antibodies indicate past infection or vaccination
• Don't unnecessarily vaccinate: Vaccination of immune individuals doesn't increase adverse events but represents an unnecessary medical intervention and cost 2
• Don't rely solely on clinical history: Laboratory confirmation of immunity through appropriate antibody testing is more reliable than patient recall of jaundice or hepatitis

The presence of anti-HAV IgG antibodies, whether from natural infection or vaccination, provides reliable, lifelong protection against hepatitis A virus, making additional vaccination unnecessary for those with documented prior infection.