Information on the Hepatitis A and B Vaccine
The current issue of the weekly medical journal "Deutsche Medizinische Wochenschrift" (DMW 2002; 127; 1581-1583) reports on a 55-year-old man who developed hepatitis A, in spite of a correct basic immunisation with the HAV/HBV vaccine Twinrix adult, 47 days after the third immunisation. The infection subsided without any further consequences. The authors concluded that a combined basic immunisation against hepatitis A and B did not assure safe protection in elderly vaccinees.
The vaccine "Twinrix adult" was approved in 1996 by the European Commission after a positive evaluation by the CPMP (Committee for Proprietary Medicinal Products) of the European Medicines Evaluation Agency (EMEA). Within the framework of the approval procedure, the immune response was evaluated with special care and thoroughness in people aged 40 years and above, since it is known that the immune response can be reduced in elderly individuals. A prospective approval study, which examined vaccinees aged between 40 and 63 years, revealed that the antibody titre was reduced in elderly vaccinees as compared to younger ones. However, it also revealed that all vaccinees were sufficiently protected against hepatitis A one month after the third vaccination. In this study, 94.4% of the vaccinees developed antibody titres against hepatitis B. After the basic immunisation was completed, antibody titres for both antigens reached levels at which a long-term protection can be assumed. Therefore, the benefit/risk balance was rated as positive for this age group, too.
In addition, another prospective study was carried out, which was published in the journal "Vaccine" (Vaccine, 19, 2001, 4710-4719). In this study, 99.5% of the vaccinees aged over 40 years revealed protective antibody titres against hepatitis A one month after the third Twinrix immunisation. 92.9% developed protective hepatitis B antibody titres.
In addition to the above-described cases, another case of vaccine failure has been reported to the Paul-Ehrlich-Institut from Germany since 1995 up to now. A 46 year-old-man had been immunised with a monovalent hepatitis A vaccine five years before he developed the disease. In addition, two cases of hepatitis A vaccine failure after immunisation with a monovalent vaccine have been published in the international literature (The Lancet, 359, 2002, 1948-1949 / Clin Inf Dis, 18, 1999, 1324-1325).
The batches reported in the DMW publication were tested and certified by the competent Belgian authority. On the basis of this test and certification, the Paul-Ehrlich-Institut released the batches for the German market in compliance with the European and German regulations. There are no indications as to insufficient quality of these batches. A relation to the quality problem revealed in the hepatitis A vaccine Vaqta reported by authors of the DMW is unlikely on the basis of the cause analysis presented here.
Current data are available from a physician's surgery which show low antibody titres in elderly vaccinees at different time intervals after the third combined hepatitis A and B immunisation. The findings of this retrospective data collection do not seem to agree with the results of the prospective clinical studies and are currently analysed further by the PEI in detail, together with the report on the isolated case described in the DMW. Possible reasons for the vaccine failure are to be identified and additional examinations must then be started if required.
According to the findings of the Paul-Ehrlich-Institut, a hepatitis A infection in spite of a full immunisation is a very rare event. It is known that the immune response is reduced in elderly individuals, both regarding the hepatitis A and the hepatitis B component. The current data and the state-of-the-art knowledge do not question the use of the immunisation. If there is any doubt, the protective effect of the immunisation can be tested in elderly vaccinees in which there is a risk of exposure by determining antibody titres.
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Updated: 14.08.2002
