Presence of anti-HBs is an indicator of clinical recovery and subsequent immunity to hepatitis B virus. This test is useful for evaluation of possible immunity in individuals who are at increased risks for exposure to the hepatitis B (ie, hemodialysis unit personnel, venipuncturists, etc). Evaluate the need for hepatitis B immune globulin after needlestick injury; evaluate the need for hepatitis B vaccine and follow immune status after hepatitis B vaccine.
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.
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. Patients 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 (vide supra). Anti-HBs can be induced by vaccination with hepatitis vaccine, now genetically engineered and free of any infective material. This vaccine so far has been safe and effective in protecting recipients from acute hepatitis B.