Chiron has withdrawn a vaccine against measles mumps and rubella, called Morupar, after data suggested it may be associated with a higher rate of adverse events than rival vaccines.

As a result, Chiron said it had been forced to write off about $6 million-worth of Morupar from its 2005 financial results, as well as $1.7 million in product returns.

Chiron said the adverse events which led to the recall and withdrawal were "within a range of those commonly associated with vaccines, such as fever, allergic reactions and swelling of the glands."

No other vaccines were affected by the recall, it said. In 2004, Chiron was forced to withdraw its Fluvirin and Begrivac flu vaccines because of manufacturing deficiencies at plants in the UK and Germany.

The company said it had supplied 5 million doses of Morupar in 2005, mainly to developing countries via international vaccine programmes, as well as to Italy, with sales running at around $10 million. Chiron’s revised 2005 figures are income from continuing operations of $1.31 per share, down three cents.

- Meanwhile, Chiron has stressed its commitment to the $5.1 billion takeover deal by Novartis after one of its shareholders, ValueAct Capital, re-iterated its ‘strong opposition’ to the deal. ValueAct has said it will try to oust Chiron chief executive Howard Pien if he participated in an investor roadshow to solicit support for the merger.