D. Give one further dose of hepatitis B vaccine – Explanation
Hepatitis B
Hepatitis B is a double-stranded DNA virus and is spread through exposure to infected blood or body
fluids, including vertical transmission from mother to child. The incubation period is 6-20 weeks.
Immunisation against hepatitis B (please see the Greenbook link for more details)
- contains HBsAg adsorbed onto aluminium hydroxide adjuvant and is prepared from yeast cells
using recombinant DNA technology - most schedules give 3 doses of the vaccine with a recommendation for a one-off booster 5 years
following the initial primary vaccination - at risk groups who should be vaccinated include: healthcare workers, intravenous drug users, sex
workers, close family contacts of an individual with hepatitis B, individuals receiving blood
transfusions regularly, chronic kidney disease patients who may soon require renal replacement
therapy, prisoners, chronic liver disease patients
- around 10-15% of adults fail to respond or respond poorly to 3 doses of the vaccine. Risk factors
include age over 40 years, obesity, smoking, alcohol excess and immunosuppression - testing for anti-HBs is only recommended for those at risk of occupational exposure (i.e. Healthcare
workers) and patients with chronic kidney disease. In these patients anti-HBs levels should be
checked 1-4 months after primary immunisation - the table below shows how to interpret anti-HBs levels:
| Anti-HBs level (mIU/ml) |
Response |
| > 100 | Indicates adequate response, no further testing required. Should still receive booster at 5 years |
| 10 – 100 | Suboptimal response – one additional vaccine dose should be given. If immunocompetent no further testing is
required |
| < 10 | Non-responder. Test for current or past infection. Give further vaccine course (i.e. 3 doses again) with testing following. If still fails to respond then HBIG would be required for protection if exposed to the virus |
Complications of hepatitis B infection
- chronic hepatitis (5-10%)
- fulminant liver failure (1%)
- hepatocellular carcinoma
- glomerulonephritis
- polyarteritis nodosa
- cryoglobulinaemia
Management of hepatitis B
- pegylated interferon-alpha used to be the only treatment available. It reduces viral replication in up
to 30% of chronic carriers. A better response is predicted by being female, < 50 years old, low HBV
DNA levels, non-Asian, HIV negative, high degree of inflammation on liver biopsy - however due to the side-effects of pegylated interferon it is now used less commonly in clinical
practice.
Oral antiviral medication is increasingly used with an aim to suppress viral replication (not in
dissimilarway to treating HIV patients)
- examples include lamivudine, tenofovir and entecavir
