What does a Hepatitis A (Hep A) Antibody (AB) total reactive result mean?

Hepatitis A Antibody Total Reactive Result

A reactive (positive) total hepatitis A antibody test indicates immunity to hepatitis A virus, meaning you have either recovered from a past infection or have been successfully vaccinated against hepatitis A. 1

What This Result Means

The presence of total anti-HAV antibodies confirms lifelong protection against hepatitis A infection. 2, 1

• Total anti-HAV antibodies persist for life after natural infection and provide complete immunity against reinfection. 2, 1
• After vaccination, protective antibody levels persist for at least 20-40 years based on kinetic models. 1
• This test does NOT distinguish between immunity from past infection versus immunity from vaccination—both produce the same positive result. 1

Clinical Implications

No further hepatitis A vaccination is needed since you already have immunity. 1

• Vaccinating someone who is already immune does not increase the risk for adverse events, but it is unnecessary and not cost-effective. 2
• The CDC recommends using commercially available tests for total anti-HAV for prevaccination testing to avoid unnecessary vaccination in immune individuals. 2

Determining the Source of Immunity

To determine whether this immunity came from past infection or vaccination, additional testing for IgM anti-HAV is necessary. 1

• If IgM anti-HAV is positive: This indicates acute or recent HAV infection, typically within the past 6 months. 1
• If IgM anti-HAV is negative: This indicates either past HAV infection with natural immunity OR immunity from HAV vaccination. 1
• IgM anti-HAV typically becomes detectable 5-10 days before symptom onset in acute infection and generally declines to undetectable levels within 6 months. 1

Important Clinical Caveat

Be aware that in very early acute hepatitis A, some patients may show anti-HAV total reactive but anti-HAV IgM non-reactive results due to differences in assay sensitivity. 3

• The total anti-HAV assay has higher sensitivity in detecting IgM antibodies than the IgM-specific assay in early infection. 3
• If acute hepatitis A is clinically suspected despite negative IgM, repeat testing 2-3 days later typically shows IgM conversion to positive. 3
• For individuals with positive total anti-HAV being evaluated for acute hepatitis, testing for other causes of hepatitis should be considered if IgM anti-HAV is negative. 1

Do Not Confuse With Hepatitis B

The CDC specifically warns against confusing hepatitis A antibody testing with hepatitis B antibody testing, which has completely different interpretation patterns. 1

• Hepatitis B core antibody (anti-HBc) positive results require additional markers (HBsAg, anti-HBs) to determine infection status. 2
• Unlike hepatitis A, hepatitis B antibody patterns can indicate chronic infection requiring ongoing management. 2