TGA finds possible cause of Fluvax convulsions but ban remains

THE ban on using Fluvax in children younger than five years will continue, the TGA has revealed, while a cause may have finally emerged for this year’s spate of febrile convulsions.

In an update to its investigation into the high rate of febrile convulsions related to CSL’s seasonal vaccine, the TGA revealed its ‘current working hypothesis’ on the cause of the fevers.

“The content of neuraminidase appears to be higher in the H1N1 strain used in the 2010 seasonal vaccine,” it said in a report posted to its website.

Excess neuraminidase enzyme activity may be pyrogenic, it said.

While the different brands of seasonal flu vaccines use the same viral strains, the vaccines may have differing levels of neuraminidase enzyme activity due to manufacturing processes.

The TGA has confirmed approved use of Fluvax would remain limited in 2011 to under-5s at high risk of complications from influenza, in whom the benefits of vaccination were deemed greater than the risk of adverse reaction.

“In addition, the Fluvax product will carry a boxed warning advising immunisation providers of the risks of febrile reactions in young children,” the TGA said.

Other paediatric influenza vaccines are not affected by the restrictions.

Meanwhile, in a separate report, the TGA has hit back at criticism of the national regulatory and safety monitoring process arising from a Western Australia Ministerial Review, saying public discussion of the issue is damaging confidence in “one of the world’s best vaccine programs”.

The review, which queried potential conflicts of interest inherent in the TGA’s cost recovery and safety investigation processes, contained “significant errors, misinterpretations and flawed conclusions”, the TGA said.

In its first formal response to former WA chief medical officer Professor Bryant Stokes’s review, the TGA said his report demonstrated a “lack of understanding” of the regulatory and monitoring frameworks.

The TGA also criticised the WA Government for setting up its own childhood flu vaccination program “outside national vaccine program guidelines” and without a specific monitoring system.

Read more at www.tga.gov.au