Forebygging av sekundærtilfeller av hepatitt A- er gammaglobulin eller vaksine best egnet?

Abstract

The hepatitis A virus (HAV) is endemic in several parts of the world. Persons travelling home shedding the virus, or the spread of contaminated food or water, are main reasons for the reported outbreaks in western countries during the last decades. Since 1992 there has been an effective vaccine available. Administered with a subsequent boosterdose (within 6-12 months), the vaccine provides sufficient immunogenity in almost 100% of persons. In the period 1945-1992 only immunglobulin derived from human serum was available as primary prophylaxis in some countries.

Vaccine is proved to be efficiant in securing lasting immunty. To what extent it can be used as secondary profylaxis is debated. Our work with this article was defined in two questions;

A) Is passive immunisation with immunoglobulin, active immunisation with inactivated vaccine, or both in combination useful ways of providing people with sufficient anti-HAV titers?

B) Is inactivated vaccine more useful than immunoglobulin in preventing secondary cases of hepatitis A ?

To answer our questions we performed a study of available litterature. We identified relevant articles through a systematic search in available databases. Randomised controlled trials were evaluated using a set of quality focused questions. Other types of articles were identified by a combination of systematic search in Medline and identification of key articles and their references.

Our findings were that all three therapies are useful (question A). Administration of immunoglobulin gives a fast respone but this is short-lasting. Inactivated vaccine gives 100% succsessfull immunisation when administred correctly and followed by a boosterdose. A combination of the two also provides suffucient anti-HAV-titers. For question B) we found that no studies have compared vaccine and immunoglobulin in preventing secondary cases. Vaccine seems quite effective, but some cases of secondary cases have been reported. Imunoglobulin is probably effective in the short term, but gives no lasting immunity.

We conclude that for healthy persons indentified within 7 days from exposure, vaccine alone can be given to prevent the development of clinical disease. Age above 50 years, delay in treatment or when persons suffer from chronic disease, immunoglobulin should be used to ensure fast and sufficient protection. The theoretical combination of both vaccine and immunoglobulin is propably to expensive to be used in most parts of the world, but is a valid choice in wealthy countries. In developing contries the focus should probably be on providing vaccination as fast as possible to prevent the development of secondary cases.