The US Department of Health and Human Services has assigned contracts with a total of just under $200 million to three European drugmakers that will provide 5.3 million doses of vaccine against the pandemic influenza strain H5N1.

GlaxoSmithKline, Sanofi-Aventis and Novartis are all tasked with supplying ‘pre-pandemic’ H5N1 vaccines, in other words vaccines designed on current predictions of the strains of the virus most likely to cause a human pandemic. Although a specific vaccine against a pandemic strain can only be produced after the infection has started to spread, it is hoped that these ‘best guess’ vaccines will offer at least partial protection and provide a first line of defence.

The new orders are intended to replace an earlier stockpile of H5N1 vaccine, based on an older form of the flu strain that has started to lose its potency and needs to be replaced.

Sanofi-Aventis is the biggest beneficiary of the contracts, with its Sanofi Pasteur subsidiary standing to receive up to $120 million for 3.7 million doses, while GSK and Novartis are in the frame for around $40 million and 800,000 doses apiece.

The contract with Sanofi is for supply of so-called ‘clade 2’ H5N1 vaccine, a strain that has been circulating in Indonesia and China. Previous deliveries of pre-pandemic H5N1 vaccine to the US government by Sanofi have been for clade 1 strains that have been encountered in Thailand, Vietnam and Cambodia.

Novartis’ contract is for egg-based production of its H5N1 vaccine, possibly alongside its proprietary MF59 adjuvant, at its vaccines production facility in Speke, Liverpool, UK. This facility was acquired along with Chiron earlier this year.

GSK will manufacture and store bulk H5N1 antigen using its recently acquired production facilities in North America. Terms of the contract also state that the company may be directed to formulate this bulk antigen at some point in the future, with or without one of its proprietary adjuvants, said GSK in a statement.

GSK vaccine likely to be preferred candidate?

Analyst Navid Malik at Collins Stewart said he believed GSK has the best vaccine candidate of the three companies, because its access to potent adjuvants means that limited supplies of the vaccine antigen can go further.

He believes GSK could eventually win the lion’s share of H5N1 flu vaccine contracts, perhaps producing as much as 100 million doses next bringing in windfall revenues of $800 million.

“The trigger for further substantial orders is a decision by the World Health Organisation (WHO) on which strain of H5N1 to nominate for stockpiling and GSK’s demonstration that its vaccine can provide cross-protection against a number of viral types,” said Malik.