CSL flu shot fits linked to viral components

In 2010, CSL's Fluvax seasonal flu vaccine was linked with cases of febrile convulsions (fits related to high fever) in the under-5s, and the company has presented the results of its investigations at the Public Health Association of Australia's 13th National Immunisation Conference. This follows warning letters from the FDA in 2010 and 2011, when the company was told that it needed to investigate the issues adequately. According to Bloomberg, CSL's shares fell by 1.2% on the news.

The study showed that Fluvax caused more fits in this group than at least one other licensed vaccine, but that the vaccine had not been linked with increased levels of convulsions in the past. The final conclusion from the company was that this was linked to the levels of virus components in the end product, rather than it being a problem with manufacturing, and that the increased levels of fits must be related to characteristics of the virus unique to the 2010 strain.

Dr Darryl Maher, vice president of medical and research at CSL Biotherapies said: "While influenza vaccines must contain virus components to stimulate sufficient protection against influenza, it appears that components of the inactivated virus retained in Fluva in 2010 overstimulated the developing immune systems of some young children compared to previous seasons."

The company is continuing studies, and in the meantime the vaccine will remain restricted to children over 5 years. Maher added: "Influenza is a serious disease and as Australia's only on-shore manufacturer of influenza vaccine, we are committed to ensuring Fluvax is safe and effective for all age groups."

- read the press release
- see the article in Bloomberg