GlaxoSmithKline Biologicals has become the first company to file for approval of a vaccine against a pandemic strain of influenza under a European fast-track system designed to accelerate the approval process.

The new system, put in place by the European Medicines Agency (EMEA) last October amidst growing concerns that a major flu pandemic is just around the corner, involves filing partial data on a potential vaccine which could be updated quickly once the actual strain causing a pandemic has been identified.

GSK’s vaccine targets the H5N1 strain of bird flu that is seen as a likely candidate to cause a new pandemic. The current outbreaks of this strain, which began in South-east Asia in mid-2003, are the largest and most severe on record. Never before in the history of this disease have so many countries been simultaneously affected, resulting in the loss of so many birds.

And this has been accompanied by an unprecedented number of human cases, with dozens of people already killed by exposure to contaminated birds. So far no human-to-human transmission has been recorded, but scientists predict that if the virus mutates to allow this to occur a pandemic will almost surely follow.

GSK’s H5N1 vaccine prototype uses an adjuvant which may boost the body’s immune response to the vaccine and allow for lower doses to be used which would be essential for treating large populations in a pandemic. The prototype may also protect against additional strains (drifted from H5N1) that could arise, according to GSK. This is significant in light of mutations that were identified in the H5N1 strain over the course of 2005.

Clinical trials with the H5N1 flu strain are planned in 2006, according to a recent GSK advisory.