Hepatitis B virus infection

01st July, 2013
By Dr Allison Glass

Hepatitis B virus infection is prevalent in South Africa. Approximately 10% of the population are chronic carriers. The virus is spread via contaminated body fluids. These include genital secretions (sexual and vertical transmission), breast milk (vertical transmission) and blood. HBV is highly infectious due to the high viral loads found in blood as well as the relative hardiness of the virus. The risk of transmission following a single needlestick injury may be as high as 30%, compared with 0.3% for HIV. Health care workers and allied hospital workers (porters, cleaners and maintenance staff) are at risk for HBV infection due to exposure to blood and other bodily fluids during their daily activities. HBV vaccination is an important strategy for minimizing transmission in this group.

WHO SHOULD BE VACCINATED?

All workers whose activities bring them into regular physical contact with patients and /or their blood or bodily fluids should be vaccinated.

SHOULD THERE BE PRE-VACCINATION TESTING?

There is no harm in vaccinating an individual who is already immune to or infected with HBV. However, in a high prevalence setting (individuals who grew up in low socioeconomic circumstances) it may be cost-effective to first screen staff for infection and immunity. An individual who has active HBV infection (HBsAg positive) or is immune to HBV (anti-HBs positive) does not require vaccination. Those with active HBV infection should be referred for appropriate investigations and treatment.

VACCINATION

3 doses of a hepatitis B vaccine should be administered at 0, 1 and 6 months.

Confirmation of successful vaccination

Anti-HBs (HBsAb) should be tested 1-3 months after the last vaccine dose. A level >10mIU/ml is considered to be protective.

BOOSTER DOSES

There is good evidence that if vaccination is successful, as demonstrated by a post-vaccination anti-HBs titre >10mIU/ml, immunologic memory will persist and protect against infection even if antibody titres drop. A routine hepatitis B vaccine booster is no longer recommended. If an individual has an exposure to HBV, the anti-HBs titre should be checked. If the titre is <10mIU/ml, a vaccine booster should be given. If the titre is >10mIU/ml, no booster is required.

NON-RESPONDERS

Non-responders are defined as individuals with anti-HBs titres that remain <10mIU/ml after appropriate vaccination. It is important to exclude active HBV infection in these individuals and a full hepatitis B screen (HBsAg, anti-HBc and anti-HBs) is recommended. Those with active infection should be referred for appropriate investigations and treatment.

Approximately 10% of adults will not respond to the first vaccination course. If anti-HBs was not tested within 3 months of the last vaccine dose, a single dose of vaccine followed by anti-HBs testing 1-3 months later will distinguish between those who are nonresponders and those with waning antibody levels. If the anti-HBs titres remains <10mIU/ml, a second vaccine series (total of 3 doses) should be administered. If the patient is >30 years old, obese or immunosuppressed, a double dose of vaccine should be used at each administration. 50-60% of those that do not respond to the first vaccination course will respond to the second. The small percentage who remain anti-HBs negative after the second vaccination course will require administration of hepatitis B immune globulin if they are exposed to HBV.

REFERENCES:

Bonanni P, Bonaccorsi G. Vaccination against hepatitis B in health care workers. Vaccine 2001, 19:2389-2394

Poland GA, Jacobson RM. Prevention of hepatitis B with the hepatitis B vaccine. New England Journal of Medicine 2004, 351;27:2832-2383

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