Disease and occurrence
Although hepatitis A is rarely fatal in children and young adults, most infected adults and some older children become ill and are unable to work for several weeks or months. The case-fatality rate exceeds 2% among those over 40 years of age and may be 4% for those aged 60 years or more.
Risk for travellers
The vaccine should be considered for all travellers to areas with moderate to high risk of infection, and those at high risk of acquiring the disease should be strongly encouraged to be vaccinated regardless of where they travel. People born and raised in developing countries, and those born before 1945 in industrialized countries, have often been infected in childhood and are likely to be immune. For such individuals, it may be cost-effective to test for antibodies to hepatitis A virus (anti-HAV) so that unnecessary vaccination can be avoided.
Vaccine
Current hepatitis A vaccines, all of which based on inactivated (killed) virus, are safe and highly effective. Anti-HAV antibodies are detectable by 2 weeks after administration of the fi rst dose of vaccine. The second dose – given at least 6 months, and usually 6–24 months, after the fi rst dose – is necessary to promote long-term protection. Results from mathematical models indicate that, after completion of the primary series, anti-HAV antibodies probably persist for 25 years or more. Booster doses are not recommended. Serological testing to assess antibody levels after vaccination is not indicated. Given the long incubation period of hepatitis A (average 2–4 weeks), the vaccine can be administered up to the day of departure and still protect travellers. The use of immune globulin is now virtually obsolete for the purposes of travel prophylaxis.
A combination hepatitis A/typhoid vaccine is available for those exposed to waterborne diseases. The vaccine is administered as a single dose and confers high levels of protection against both diseases. A second dose of hepatitis A vaccine is needed 6–24 months later and boosters of typhoid vaccine should be given at 3-yearly intervals.
A combination vaccine that provides protection against both hepatitis A and hepatitis B may be considered for travellers who may be exposed to both organisms. Primary immunization with the combined hepatitis A and B vaccine consist of three doses, given on a schedule of 0, 1 and 6 months. According to the manufacturer’s instructions, this combination vaccine may also be administered on days 0, 7 and 21, with a booster dose at 12 months. Minor local and systemic reactions are fairly common. Minimum age is 1 year.
Type of vaccine: Inactivated, given i.m.
Number of doses: Two
Schedule: Second dose 6–24 months after the first
Booster: May not be necessary
Contraindications: Hypersensitivity to previous dose
Adverse reactions: Mild local reaction of short duration, mild systemic reaction
Before departure: Protection 2–4 weeks after first dose
Recommended for: All non-immune travellers to endemic areas
Special precautions: None