There are around 1.4 million cases of Hepatitis A reported worldwide every year; the actual figure could be ten times higher. Hepatitis A is one of the most common vaccine-preventable infectious diseases in the world. Effective vaccines against hepatitis A have been available for over a decade and are recommended for people at risk of infection such as populations in some less-developed regions of the world and western travellers to those regions. Two or three doses of vaccine provide long-term immunity against the infection. However, there is no worldwide consensus on how long protection will last or whether there is a need for HAV booster vaccinations. In most countries, booster-vaccination policy is guided by manufacturers' recommendations, national authorities, or both.
Jangu Banatvala (Emeritus Professor of Virology, Guy's, King's & St Thomas' School of Medicine, London, UK) and colleagues describe the outcome of a meeting held last year to review the long-term effectiveness of HAV vaccine in different population groups. Data have shown that after a full primary vaccination course, protective antibody amounts persist beyond 10 years in healthy individuals, and underlying immune memory provides protection far beyond the duration of anti-HAV antibodies. The group concluded that there is no evidence to lend support to HAV booster vaccination after a full primary vaccination course in a healthy individual. However, further investigations are needed before deciding if boosters can be omitted in special patient-groups.
Jangu Banatvala comments: "Evidence is accumulating to show that HAV vaccine elicits immune memory that persists even after loss of detectable antibody. We recommend that reliance be placed on immunological memory rather than booster doses to protect against symptomatic infection. The recommended schedules for HAV vaccines consist of a complete primary course, as described in the product license. Results of preliminary studies show that even one dose induces long-term immune memory. Therefore, the primary course can be continued without restarting, even after an extended interval before the second dose. Additional studies are needed to explore the long-term efficacy of a single dose. To date, no data lend support to the need for booster doses of HAV vaccine in immunocompetent individuals who have received a full vaccination course."
Professor Jangu E Banatvala, Church End, Henham, Bishop's Stortford, HERTS CM22 6AN, UK;
Dr Pierre Van Damme, University of Antwerp, Epidemiology & Community Medicine, Centre for the Evaluation of Vaccination, Universiteitsplein 1, 2610 Wilrijk, Belgium;