From the Guidelines
A reactive Hepatitis B surface antibody (anti-HBs) test result indicates immunity to Hepatitis B virus, which could be from either successful vaccination or from a previous infection that your body has cleared. This is based on the most recent and highest quality study available, which emphasizes the importance of anti-HBs in assessing immunity to HBV infection 1.
Key Points to Consider
- If your anti-HBs level is greater than or equal to 10 mIU/mL, you are considered protected against Hepatitis B infection and no further action is needed regarding Hepatitis B vaccination, as indicated by the guidelines from the Advisory Committee on Immunization Practices 1.
- This immunity is generally considered long-lasting, though in some cases antibody levels may decline over time, but most people with a history of adequate response remain protected due to immune memory 1.
- If you're concerned about your immunity status, especially if you're in a high-risk occupation or have ongoing exposure risks, you could discuss with your healthcare provider about checking other Hepatitis B markers (such as anti-HBc) to distinguish between vaccine-induced immunity and immunity from past infection 1.
- For most people with reactive anti-HBs results, no booster doses of the vaccine are currently recommended unless you are immunocompromised or have specific medical conditions that might affect your immune response, as suggested by the guidelines for cancer patients 1.
Important Considerations for Specific Groups
- Patients with malignancies who are HBsAg positive and/or HBcAb positive are at risk for HBV reactivation with cytotoxic chemotherapy, and serum HBV DNA testing before the start of therapy may help define their risk of reactivation 1.
- Vaccination against HBV should be strongly considered in HBV-naïve patients (i.e., negative for HBsAg, HBsAb, and HBcAb) who are about to undergo immunosuppressive therapy 1.
From the Research
Hepatitis B Surface Antibody
A reactive Hepatitis B (Hep B) surface antibody indicates that an individual has been vaccinated against Hepatitis B or has recovered from a Hepatitis B infection and is now immune 2, 3.
Immunity and Protection
The presence of hepatitis B surface antibody (HBsAb) is generally considered protective against Hepatitis B infection, but the level and persistence of this antibody can vary 2. In some cases, individuals with isolated anti-HBs may not be fully protected against Hepatitis B, especially if the antibody levels are low 2.
Reactivation of Hepatitis B
In rare cases, Hepatitis B reactivation can occur in individuals with prior exposure to HBV and protective levels of HBsAb, a phenomenon known as reverse seroconversion 4. This can happen in patients undergoing immunosuppressive therapy, such as those receiving umbilical cord allogeneic hematopoietic cell transplantation 4.
Key Points
- A reactive Hepatitis B surface antibody typically indicates immunity to Hepatitis B 2, 3
- The level and persistence of HBsAb can affect the level of protection against Hepatitis B infection 2
- Reactivation of Hepatitis B can occur in individuals with prior exposure to HBV and protective levels of HBsAb, especially in immunosuppressive settings 4, 5
- HBsAg genetic mutations can contribute to immune escape and HBV reactivation upon immunosuppression 5