Enzira/CSL Biotherapies and Viroflu/Inflexal V influenza vaccines and risk of febrile reactions in children under 5 years

Use alternative vaccines in under 5s and report suspected adverse reactions

Article date: October 2011

Prescribers are reminded that Enzira and CSL Biotherapies generic influenza vaccines (both manufactured by CSL and marketed by Pfizer) should not be given to children younger than 5 years. These vaccines are not authorised for use in this age-group after the increased risk of febrile convulsions observed in Australia last year (see Drug Safety Update, Oct 2010).

CSL also supplies starting materials for the manufacture of another flu vaccine, Viroflu and Inflexal V (both manufactured by Crucell UK), which will be supplied in the UK this year. It is not known if Viroflu/Inflexal V may also carry a risk of febrile convulsions. However, because of a higher than expected frequency of fever above 39°C seen in a clinical trial in children, the licence for Viroflu/Inflexal V has been amended to advise caution when using in children younger than 5 years. Because a risk of febrile convulsions cannot be excluded, Viroflu/Inflexal V should only be used if a suitable alternative flu vaccine is not available. This advice is endorsed by the Department of Health.

It is important that children older than 6 months who are in clinical risk groups receive flu vaccination, and the alternative vaccines should be used as recommended (for further information, see letter from the Department of Health on the influenza immunisation programme 2010/11.

We proactively monitored the safety of the CSL vaccines and other seasonal flu vaccines during the 2010–11 flu season, with help from Yellow Card reporters. We found no evidence of an increased risk of febrile convulsions in children associated with other seasonal influenza vaccines, suggesting that this risk is limited to the Enzira and CSL Biotherapies generic influenza vaccines (see Drug Safety Update, Jan 2011). Viroflu/Inflexal V was not used in the UK during 2010–11.

In the forthcoming seasonal immunisation campaign we will continue to closely monitor the safety of all flu vaccines. In particular, we ask you to help by promptly reporting any cases of febrile convulsion occurring within 72 hours of receiving a flu vaccine. It is very important that the brand name of the vaccine given, and batch number if available, are reported to us. If you do not have this information at hand, please still report to us and we will follow-up with you for further information.

Reports of febrile convulsions or any suspected adverse reaction can be sent online to www.yellowcard.gov.uk 

Further information

BNF section 14.4 Vaccines and antisera 

Article citation: Drug Safety Update Oct 2011, vol 5 issue 3: S1.

Published 13 October 2011