Pandemic influenza: GSK announce progress in low-dose vaccine for H5N1 bird flu

(8 August 06)

If a pandemic influenza vaccine is to reach a large population, it is important that the dose needed to produce immunity is small – so the same amount of product can get to more people. Now GlaxoSmithKline (GSK) , the pharmaceutical company, have announced an experimental vaccine against H5N1 bird flu that is immunogenic at the lowest dose yet – 3.8 micrograms.

However, bird flu is not a pandemic virus, as so far it does not transmit effectively between people, and even the GSK vaccine needs further development, and testing in clinical trials. But the result is promising – if H5N1 bird flu mutates to become a transmissible pandemic flu, as is widely feared, and if the H5N1 epitopes (virus surface molecules) are unchanged, the GSK vaccine could be effective.

The results were based on an interim analysis of a clinical trial conducted in Belgium, which involved 400 healthy adults aged 18-60 years of age, GSK reported. The vaccine tested was produced from inactivated H5N1 virus and contained a novel, proprietary adjuvant. Over 80% of subjects, who received 3.8µg of antigen with the adjuvant, demonstrated a seroprotective immune response, according to standard criteria. The subjects were not exposed to live virus to test the response, however.

Commenting on the data, Jean-Paul Garnier, GSK’s Chief Executive Officer, said: “There is still a lot more work to be done with this programme, but this validation of our approach provides us with the confidence to continue developing the vaccine, including assessment of its ability to offer cross-protection to variants of the H5N1 strain. All being well, we expect to make regulatory filings for the vaccine in the coming months.”

According to the UK Guardian newspaper, however, GSK estimates a price of around US$8 – prohibitive for developing countries.

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