These vaccines have been associated with a higher-than-expected risk of febrile convulsions in children, the DoH in England’s director of immunisation has warned in a letter sent out to GPs dated Wednesday.

Professor David Salisbury said data from Australia show there has been a higher than expected increase in febrile convulsions in children related to the use of Fluvax (manufactured by CSL Biotherapies).

Fluvax is the same product that will be marketed in the UK for the 2010/11 influenza vaccination season by Pfizer as Enzira and by CSL Biotherapies as a generic influenza vaccine.

Professor Salisbury said: ‘Given the availability of other influenza vaccine products, you should avoid offering Enzira or CSL Biotherapies' generic influenza vaccine marketed by Pfizer to children aged under five years.

‘Please check which manufacturer's products you have ordered (including the possibility that you have ordered CSL Biotherapies generic influenza vaccine) and ensure that you have stocks of alternative influenza vaccines to give to such children in the 2010/11 influenza vaccination programme.’

He stressed the importance of children over six months of age who are in clinical risk groups receiving influenza vaccination.

Evidence suggests a rate of febrile convulsions of about one per 100 for children vaccinated with Fluvax. This increased risk appears to be a product-specific reaction, Professor Salisbury said.

Evidence has so far not indicated a similar level of risk with other products, but the MHRA will monitor the situation and issue further advice ahead of the 2010-11 vaccination programme, Professor Salisbury said.

In a statement issued in response to the letter, a Pfizer spokesman said that that both companies were aware of the reported increase in febrile convulsions in children.

'The cause of the unexpected increased frequency of febrile convulsions remains unknown and investigations continue,' Pfizer said. 'Pfizer and CSL are working closely with regulatory authorities, health agencies and distribution partners to determine the most appropriate way to provide influenza vaccine for the Northern Hemisphere 2010/2011 influenza season.'

It added: 'While, Pfizer supports the current precautionary approach to the use of our influenza vaccine in children under five years of age, it should be noted that the vast majority of patients in the UK receiving the influenza vaccine are adults, and febrile convulsions are not seen in the adult population.

'In addition, there is no evidence that the vaccine poses any increased risks to other groups, including pregnant women and those aged over 65.'

 

• Click here to view our Outbreaks and Infections Resource Centre