A report in the lancet says that an adjuvanted form of GlaxoSmithKline's experimental flu vaccine could well work against more than one strain of avian influenza, and allow stockpiles to last longer.

The adjuvanted formulation of the firm’s experimental H5N1 influenza vaccine is up to six times more effective at producing an immune response than the same dose of the non-adjuvanted version, claims the study, which is important news when it comes to preparing for a pandemic as they suggest that the "number of pre-pandemic vaccine doses can be stretched 20- to 25-fold," according to Suryaprakash Sambhara of the US Centers for Disease Control and Prevention.

In the study, 400 adults were administered one of four antigen doses, which contained a Vietnamese strain of the H5N1 virus, with or without the proprietary ASO3 adjuvant. The results showed that the lowest dosage of adjuvanted vaccine produced an immune response in 84% of patients and 77% who received the lowest dose of the adjuvanted vaccine had a cross-immune response against a separate, Indonesian strain of H5N1.

Vaccines are presently produced in eggs, which are prone to contamination and could be in short supply when an outbreak occurs but combining a vaccine with the adjuvant, a special oil-in-water emulsion, means that supplies can be stretched and potentially be produced in advance before it was known what strain was causing a pandemic.

"This vaccine appears to be an important step forward in our ability to protect against the pandemic threat,'' Mr Sambhara and co-author Gregory Poland said in an accompanying editorial. The study appeared just as GSK and Baxter have just received contracts worth £155.4 million from the UK government to supply an influenza vaccine as soon as a pandemic strain is identified and made available by the World Health Organization.