Presence of antibody to hepatitis B surface antigen (anti-HBs) is used to determine immune status to HBV or disease progression in individuals infected with HBV. Anti-HBs levels can be measured to determine if vaccination is needed, or following a vaccination regimen, to determine if protective immunity has been achieved.

- Anti-HBs usually can be detected several weeks to several months after HBsAg is no longer found, and it may persist for many years or for life after acute infection has been resolved.

- It may disappear in some patients, with only antibody to core remaining.

- People with this antibody are not overtly infectious.

- Presence of the antibody without the presence of the antigen is evidence for immunity from reinfection, with virus of the same subtype.

What is the Hepatitis B virus?

Hepatitis B virus (HBV) infection, also known as serum hepatitis, is endemic throughout the world. The infection is spread primarily through blood transfusion or percutaneous contact with infected blood products, such as sharing of needles among injection drug users. The virus is also found in virtually every type of human body fluid and has been known to be spread through oral and genital contact. HBV can be transmitted from mother to child during delivery through contact with blood and vaginal secretions, but it is not commonly transmitted via the transplacental route.

The incubation period for HBV infection averages 60 to 90 days (range of 45 - 180 days).

What are common symptoms?

Common symptoms include:

- malaise,

- fever,

- gastroenteritis,

- and jaundice (icterus).

After acute infection, HBV infection becomes chronic in 30% to 90% of infected children younger than 5 years of age and in 5% to 10% of infected individuals age 5 or older. Some of these chronic carriers are asymptomatic, while others progress to chronic liver disease, including cirrhosis and hepatocellular carcinoma.

When you are exposed to hepatitis B, your body mounts an immune reaction against it as an invader. This happens whether you are exposed due to blood or sexual contact or if you are vaccinated with the hepatitis B vaccine.

Notes:

- Presence of anti-HBs is not an absolute indicator of resolved hepatitis infection, nor of protection from future infection. Since there are different serologic subtypes of hepatitis B virus, it is possible (and has been reported) for a patient to have antibody to one surface antigen type and to be acutely infected with virus of a different subtype. Thus, a patient may have coexisting HBsAg and anti-HBs. Transfused individuals or hemophiliacs receiving plasma components may give false-positive tests for antibody to hepatitis B surface antigen.

- Individuals who have received blood component therapies (eg, whole blood), plasma, or intravenous immunoglobulin infusion) in the previous 3 to 6 months may have false-positive hepatitis B surface antibody (anti-HBs) results due to passive transfer of anti-HBs present in these products.