Protocol for interpretation of anti-HBs result after pre-exposure vaccination

The schedule for the particular vaccine should always be checked before proceeding

• vaccine is given intramuscularly into the deltoid region. The buttock should not be used as this reduces the efficacy of the vaccine, but the anterolateral thigh may be used
• the immune status is checked 1-2 months after the third dose of vaccine. The antibody (anti-HBS) levels defines further intervention
• an example of an immunisation schedule following the result of the antibody level after the primary vaccination course is presented

There are many different immunisation schedules for hepatitis B vaccine which depend on the vaccine product used and how quickly protection is needed for pre or post exposure.

Testing for response to vaccination

Hepatitis B vaccines are highly effective; around 90% of adults respond to vaccines adequately.

Poor responses are mostly associated with age over 40 years, obesity and smoking

• lower seroconversion rates have also been reported in people who have alcohol dependency, particularly those with advanced liver disease
• patients who are immunosuppressed or on renal dialysis may respond less well than healthy individuals and may require larger or more frequent doses of vaccine
• vaccine is not effective in patients with acute hepatitis B, and is not necessary for individuals known to have markers of current (HBsAg) or past (anti-HBc) infection. However, immunisation should not be delayed while awaiting any test results for current or past infection
• testing for evidence of immunity post immunisation (anti-HBs) is not routinely recommended although is required for particular risk groups e.g. those with occupational exposure.

Those at risk of occupational exposure

• in those at risk of occupational exposure, particularly healthcare and laboratory workers, anti-HBs titres should be checked one to two months after the completion of a primary course of vaccine
  • under the Control of Substances Hazardous to Health (COSHH) Regulations, individual workers have the right to know whether or not they have been protected
    • such information allows appropriate decisions to be made concerning postexposure prophylaxis following known or suspected exposure to the virus
      
      
• antibody responses to hepatitis B vaccine vary widely between individuals
  • preferable to achieve anti-HBs levels above 100mIU/ml, although levels of 10mIU/ml or more are generally accepted as enough to protect against infection
  • some anti-HBs assays are not particularly specific at the lower levels, and anti-HBs levels of 100mIU/ml provide greater confidence that a specific response has been established

Assessment of response to hepatitis B vaccine:

• responders with anti-HBs levels greater than or equal to 100mIU/ml do not require any further primary doses
  • in immunocompetent individuals, once a response has been established further assessment of antibody levels is not indicated
    
    
• responders with anti- HBs levels of 10 to 100mIU/ml
  • should receive one additional dose of vaccine at that time
  • in immunocompetent individuals, further assessment of antibody levels is not indicated
  • current advice is that healthcare and laboratory workers should be offered a single booster dose of vaccine, once only, five years after the primary immunisation
    
    
• anti-HBs level below 10mIU/ml
  • classified as a non-response to vaccine, and testing for markers of current or past infection is good clinical practice
  • in non-responders, a repeat course of vaccine is recommended, followed by retesting one to two months after the second course
  • those who still have anti-HBs levels below 10mIU/ml, and who have no markers of current or past infection, will require HBIG for protection if exposed to the virus (1)

Notes:

• in chronic renal failure
  • protection may persist only as long as anti-HBs levels remain above 10mIU/ml. Antibody levels should, therefore, be monitored annually and if they fall below 10mIU/ml, a booster dose of vaccine should be given to patients who have previously responded to the vaccine (1)
    
    
• other guidance has been detailed about how to manage an anti-HBS response of below 10 iu per litre (2)
  • if the anti-HBS level is below 10 iu per litre then check core antibody (anti-HBC)
    • if the anti-HBC is positive then this indicates HBV infection in the past
    • if the anti-HBC is negative then repeat or complete second accelerated full course. A response may be achieved via the use of a higher-dose vaccine
    • if no response and anti-HBC negative then the patient should be advised that he is not immune and will require hepatitis B specific immunoglobulin after high-risk exposure
  • if there is any response (>= 10 iu per litre) then the patient requires a booster 5 years later

Reference:

• The Green Book. Chapter 18 - Hepatitis B (April 2019)
• Prescriber (2000), 11, (7), 45-54.