Aventis Pasteur withdraws VAQTA hepatitis A vaccines

A coordinated withdrawal of the VAQTA hepatitis A vaccines manufactured by Aventis Pasteur took place throughout member states of the European Union (EU) last week. The withdrawal applies to both adult and paediatric preparations (launched in 1997 and 1998, respectively) and to all batches of vaccine currently within their expiry date. Previous batches that have now expired (including those marketed under their generic name, “Hepatitis A vaccine, purified, inactivated, for adults”) may also have been affected. Those holding stocks of vaccine are requested to quarantine all affected batches. Aventis Pasteur MSD is contacting customers to arrange return of unused doses. For medical queries contact Aventis Pasteur MSD’s Vaccine Information Service.

The antigen content in some prefilled syringes was found to be below the established minimum specification on retesting of a sample of vaccine doses in Germany. It is therefore possible that some patients who have received any of the formulations of VAQTA may be inadequately protected against infection with hepatitis A virus or have reduced duration of protective immunity, or both. The problem with vaccine potency seems to be sporadic, possibly related to the filling process, which means that it is not possible to predict which recipients might be inadequately protected. People who have received VAQTA products can be reassured that the vaccine is not being recalled for reasons of safety.

No major threat to public health is anticipated since most hepatitis A vaccinations are given for short term low risk exposures during travel abroad. Hepatitis A virus transmission has been effectively reduced by the high level of hygiene and sanitation in most member states of the EU, and vaccination has made a very small contribution to its epidemiology in most countries (1).

People who have received VAQTA in the past and require ongoing protection can be revaccinated with an alternative brand of vaccine or tested for serological evidence of immunity. The response from public health authorities to the VAQTA withdrawal has varied in different countries. In the UK, the Department of Health has made recommendations (2) that apply only to those at continuing risk of hepatitis A who have been immunised with VAQTA products. It is recommended that:

those who have previously been immunised with these products should start their immunisation schedule again with another hepatitis A vaccine product;
those who have been immunised with one of these products in anticipation of travelling to high risk areas for hepatitis A in the near future, for example for a ‘winter sun’ holiday, should be reimmunised immediately, with another product. Hepatitis A vaccine is effective prevention even if given immediately before departure (3); and
those who have received both a VAQTA product and another hepatitis A vaccine product as part of their immunisation should, for continuing protection, receive a further dose of another hepatitis A vaccine product. A period of at least six months should have elapsed between the two doses of the alternative vaccines (4).

Implementing these recommendations may be particularly difficult in certain hard to reach high risk groups who are at ongoing risk, such as injecting drug users (1).

No vaccine failures have been reported to the regulatory authorities in EU countries. Surveillance data from the Public Health Laboratory Service (PHLS) for England and Wales include very limited information on vaccination status, but three cases of hepatitis A virus infection have been reported in previously vaccinated people in England and Wales, one in 1997 and two in 1998. No outbreaks have been reported in England and Wales that could be traced to failure of vaccine.

On the basis of the information that has been made available, most recipients of VAQTA are likely to have adequate antibody levels. If on revaccination, a local reaction occurs, this should be reported in the usual way to the relevant authorities.

References:

1. Crowcroft NS, Walsh B, Davison K, Gungabissoon U. Guidance for control of hepatitis A virus infection. Commun Dis Public Health 2001; 4(3): 213-27.

2. Department of Health. Hepatitis A vaccine. Public Health Link/CMO’s urgent communication (CEM/CMO/2001/16). (http://www.doh.gov.uk/cmo/cmo01_16.htm)

3. CDSC. Human normal immunoglobulin (HNIG): lack of availability for travellers. Commun Dis Rep CDR Wkly 2000; 10 (34): 301. (http://www.phls.co.uk/publications/CDR00/cdr3400.pdf)

4. Department of Health. Immunisation against infectious diseases. London: The Stationery Office, 1996

Reported by Natasha Crowcroft (ncrowcro@phls.org.uk), Public Health Laboratory Service Communicable Disease Surveillance Centre, London, England.

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