Europe’s drug regulator has suspended sales of the Sanofi Pasteur’s vaccine Hexavac, as a precautionary measure on concerns that it may not provide adequate protection against hepatitis B.

According to the agency, experts have identified decreased immunogenicity, the body’s response to defend itself against a disease, of the hepatitis B component. This is believed to be caused by variability in the production process, which could lead to a reduction in the vaccine’s long-term protection against hepatitis B. The problem does not affect the vaccine's protection against other diseases and there is no immediate concern for children already vaccinated with Hexavac, stressed the EMEA.

Consequently, while sales of the vaccine are suspended, the agency has requested that the company, which operates as a joint venture between the French group Sanofi-Aventis and US drugmaker Merck & Co in Europe, design a follow-up programme to determine whether revaccination is necessary at a later stage.

Hexavac first hit the European market in 2000 for the protection of infants and children against diphtheria, tetanus, whooping cough, hepatitis B, polio and Haemophilus influenzae type B.

The product currently represents around 10% of Sanofi-Aventis’ vaccine sales, according to a company spokesperson, but Code Securities analyst Paul Diggle expects the impact of its marketing suspension to be fairly minimal. He has forecast that it will cost Sanofi-Aventis around 100 million euros in turnover, a relatively small amount considering that the firm’s total revenues are around 25 billion euros, reports Reuters.

However, UK drug giant GlaxoSmithKline is rubbing its hands at the prospect of boosting sales of its rival vaccine Infanrix hexa, and is planning to step up its production and supplies. “GSK is committed to ensuring that children requiring vaccination in Europe are unaffected by any resulting shortage of supply and we are moving quickly to fill the gap,” stated Jean Stephenne, President of GSK Biologicals. “We are already preparing shipments of sufficient supplies of Infanrix hexa to the European markets affected by this recommendation and we are working with the authorities to ensure their rapid release.”