What Does a Positive HAV Antibody Test Mean?

A positive HAV antibody result refers to the presence of antibodies against the hepatitis A virus (HAV) in the blood. These antibodies can be of two types: IgM and IgG. IgM antibodies typically appear early during infection and remain in the system for a shorter period, making them useful for diagnosing recent or acute infections. If a patient tests positive for anti-HAV IgM, it's important to evaluate their liver function. In cases where liver enzymes are elevated, a diagnosis of acute hepatitis A can be made.

However, not all IgM-positive results indicate active disease. Some individuals may test positive for anti-HAV IgM without showing symptoms or having abnormal liver function, which could suggest a recent, asymptomatic infection. This is known as a subclinical or "silent" infection, where the person was exposed to the virus but experienced no noticeable illness.

On the other hand, a positive IgG antibody test indicates past exposure to HAV. IgG antibodies usually develop after the initial infection has resolved and can provide long-term immunity. This means that someone who has recovered from a previous hepatitis A infection—or someone who had an asymptomatic infection—may show only IgG antibodies in their blood.

Distinguishing between a current and past infection requires careful evaluation of both antibody types and liver function tests. Because many HAV infections are subclinical, people may discover they have antibodies during routine blood work without ever having experienced symptoms. It's important to understand that a positive HAV antibody test does not always mean a person has had hepatitis A disease—it may simply reflect prior exposure without illness.