From the Guidelines
Hepatitis A total antibody reactive indicates that a person has developed immunity to the hepatitis A virus, either through past infection or vaccination, as evidenced by the presence of antibodies in their blood. This is a positive test result that shows the immune system has developed a response to hepatitis A, providing lifelong protection against the disease 1. The total antibody test detects both IgM and IgG antibodies, with IgG antibodies typically indicating immunity from past infection or vaccination, while IgM antibodies suggest a current or recent infection 1.
Key Points to Consider
- The presence of total antibodies against hepatitis A virus (HAV) indicates a protective immune response to infection, vaccination, or passively acquired antibody 1.
- Total anti-HAV testing is used to measure the prevalence of previous infection or to determine whether a person with an indication for pre-exposure prophylaxis is already immune 1.
- No specific treatment is needed for a positive hepatitis A antibody test alone, as it often indicates immunity, but individuals experiencing symptoms and with IgM antibodies present should rest, maintain hydration, avoid alcohol, and follow up with their healthcare provider.
Clinical Implications
The detection of total antibodies against HAV is beneficial as it generally means the person is protected against future hepatitis A infections, since the virus typically confers lifelong immunity after recovery from infection 1. This information is crucial for determining the need for vaccination or other preventive measures, especially in individuals at high risk of exposure to the virus.
From the Research
Hepatitis A Total Antibody Reactive Results
- Hepatitis A total antibody reactive results are generally interpreted as immunity to HAV, but some early acute hepatitis A patients may show the same results 2.
- The anti-HAV total assay has higher sensitivity in detecting IgM antibodies than the anti-HAV IgM assay, which can lead to anti-HAV IgM non-reactive but anti-HAV total reactive results in early acute hepatitis A patients 2.
- The presence of virus-specific IgM in acute and early convalescent phase sera indicates a specific IgM response to hepatitis A virus 3.
Interpretation of Total Antibody Reactive Results
- Total antibody reactive results can be interpreted as immunity to HAV, but the accuracy and precision of immunoassays for total or anti-HAV IgG determination may vary, especially around the immunity threshold of 20 IU/L 4.
- The avidity index (AI) of anti-HAV IgG can be used to distinguish acute infection from immune reactivation, with patients with a history of prior infection having AIs of >70% and patients with acute HAV infection having AIs of <50% 5.
Detection of Anti-HAV IgM and IgG Antibodies
- The detection of anti-HAV IgM and IgG antibodies can be improved using recombinant proteins, such as r3CPro, which exhibited higher sensitivity and specificity in detecting both anti-HAV IgM and IgG antibodies during the acute phase of the disease 6.
- The capsid protein-based assays showed overall less sensitivity for detection of both anti-HAV IgM and IgG antibodies as compared to whole virus antigen-based commercial assays 6.