Hepatitis A Vaccination

Hepatitis A (HAV) is one of the most common vaccine preventable diseases in the world with an incidence of 1.5 million cases per year worldwide.¹ An epidemic was described by Hippocrates in the fifth century BC, but not until 1979 was the single stranded RNA virus (of the Picornaviradae family) grown in a laboratory. There is no specific treatment and the first effective vaccine was introduced in 1992.

Hepatitis A infection is common in less developed countries where hygiene is poor. Spread is mainly by the faecal-oral route but also by person to person contact (although food and drink contamination may be involved). The infection can be silent, especially in children, and the hepatitis can be with or without jaundice. Fulminant hepatitis is rare (0.1%). Mortality rises with age from 0.1% in under 4's to 2% in the over 60's. Recovery may take 6-12 months. There is no chronic carrier state. The increasing pool of susceptible, non-immune people in developed countries and more foreign travel pose an increasing risk of infection. Older pateints are at increased risk of both infection and the serious sequelae from infection.

The vaccines are all formaldehyde inactivated and prepared from virus strains (GBM, HM 175 or RG-SB) grown in human diploid cells. Three (Havrix®, Vaqta®, Avaxim®) are absorbed onto an aluminium hydroxide adjuvant but Epaxal® contains inactivated virus particles attached to phopholipid vesicles. They can be used interchangeably.

They are supplied as a slightly opaque suspension (except Epaxal® which is an emulsion, and particle free) in 0.5-1ml syringes and storage should be protected from light between 2-8° Celsius. They should not be diluted or mixed. Discard if frozen. Shelf-life is 2 years, 3 years for Avaxim®. Potency of Vaqta® is little affected by exposure to 28° Celsius for 3 months but this is not recommended for storage.

They should be shaken before use and given into the deltoid region intramuscularly. In cases of severe bleeding diathesis the subcutaneous route is licensed for Avaxim® and Havrix Monodose®. Other vaccines can be given at the same time, but a different site should be used.

• Primary vaccination. This consists of 1 dose of vaccine, correct for age. Seroconversion is 88% at 2 weeks rising to 95% and producing antibodies for up to 1 year.
• Reinforcing dose. This is given 6-18 months after the primary dose depending on which vaccine has been given. Seroconversion is virtually 100% and lasts at least 25 years and possibly a lifetime.^2,1 The reinforcing dose can be delayed for between 3 and 4 years depending on which vaccine is given. For those at continued risk a further booster at 20 years is now recommended (used to be 10 years).³

- recommended for those at risk of exposure to HAV or of complications from getting HAV.

• Travellers to moderate to high risk areas i.e. any country outside northern and western Europe, North America, Japan, New Zealand and Australia. The Indian subcontinent carries the highest risk - see country specific travel advice.
• Patients with chronic liver disease including hepatitis B and C.⁴
• Haemophiliacs receiving Factor VIII and IX concentrates (subcutaneously).
• Intravenous drug users (with hepatitis B vaccine or using combined vaccine).
• Certain occupations (recommended in laboratory workers likely to be exposed to the virus, staff of large residential institutions, sewerage workers, workers with primates. Should be considered in food handlers, staff in day-care facilities. Military personnel often require vaccination).
• People at risk because of their sexual behaviour (mainly anal intercourse).
• Management of outbreaks of HAV.

• Acute febrile illness, but not minor non-febrile illnesses.
• Previous severe reaction to hepatitis A vaccine.
• Hypersensitivity to components of the vaccine.
• Pregnancy and lactation unless definite risk of infection.
• Children under age 1 (children aged 1-16 have junior vaccine).

• Local: mild, transient soreness and redness.
• General: flu-like symptoms.
• Mild, temporary elevation of liver enzymes has been reported.

Combinations with hepatitis B (Twinrix®) and typhoid (Hepatyrix®, ViATIM®) have been developed and these may offer advantages of convenience when several vaccines are needed. However the schedules are slightly different as are the eligible ages.

• Hepatitis A and hepatitis B combined (Twinrix and Twinrix Paediatric):Twinrix Adult, for age 16 and over- paediatric version for ages 1-15 years. Standard schedule is three doses (1 month later, third 6 months after first or 0,7 and 21 days for accelerated schedule).
• Hepatitis A and Typhoid combined (Hepatyrix® and ViTIM®):Where this is used booster of Hepatitis A single antigen vaccine will be required 6-12 months later and a booster of typhoid 3 years later as usual.

This is prepared from pooled plasma and can be used for more immediate passive immunisation. Antibody levels achieved are lower and last only 4-6 months.

• Can be given with vaccine different site.
• No longer recommended for travel prophylaxis.
• Useful in management of outbreaks.⁵

See viral hepatitis.
Advice on managing these can be sought from the Consultant in Communicable Disease Control or from the PHLS Communicable Disease Surveillance Centre. Vaccination can interrupt outbreaks as demonstrated in Alaska and Slovakia.