GlaxoSmithKline says it is only months away from filing for approval of a vaccine against the H5N1 strain of avian influenza, currently thought to be the most likely to cause a flu pandemic in humans, after promising results in clinical trials.

An interim analysis of a 400-patient trial conducted in Belgium suggests that GSK’s formulation - which includes just 3.8mcg of H5N1 antigen and includes a novel, proprietary adjuvant to boost its activity - stimulated a protective immune response in over 80% of subjects.

Trial participants were vaccinated twice during the course of the trial and four different levels of antigen dose were tested, with 3.8mcg being the lowest dose assessed.

The use of the adjuvant means that scarce supplies of the H5N1 antigen can be stretched further, and GSK’s chief executive Jean-Pierre Garnier told the Today programme on the BBC’s Radio 4 this morning that it could be in a position to produce ‘hundreds of millions’ of doses by the end of the year, and could also cost as little as £4 a dose, roughly equivalent to the price of seasonal flu vaccines.