The use of MedImmune's 'reverse genetics' system has seen rapid growth with Sanofi-Pasteur, Novartis, CSL Limited of Australia and now GSK all having licensed the vaccine production technology to aid their influenza vaccine programs.

While financial details of the deal were disclosed, MedImmune will receive an upfront payment as well as the potential to receive royalties on certain vaccine stockpiles or sales of influenza products developed using the technology.

"MedImmune is pleased to enter into a fourth agreement to license our reverse genetics technology to manufacturers," said Jonathan Klein-Evans, MedImmune's vice president for intellectual property.

"Making this important technology available to the vaccine development team at GlaxoSmithKline and their peers at other companies may have a significant positive impact on the manufacturing of influenza vaccines due to the efficiency and reliability of the process."

GSK are already one of the largest vaccine produces in the world, with the company claiming that every 2.5 seconds somebody in the UK receives a GSK manufactured vaccine.

The company has been investing in its vaccine production ability over the last few years, buying a US production facility from Wyeth for €80m in 2005 to "develop the next generation of vaccines" for influenza using tissue culture technology.

Last month, the company was awarded a contract to provide 22.5m doses of bulk H5N1 flu antigen to the US stockpile.

The classical method of producing flu vaccines requires a lot of time consuming guesswork as different combinations of flu strains are injected into eggs until the desired antigens are produced.

This can significantly hold up flu vaccine production, something that could cause a large loss of life in the face of a flu pandemic.

The reverse genetics technology, also known as 'plasmid rescue', enables scientists to simply assemble vaccines by assembling genes that code for the desired features.

This has two major advantages over the traditional method as it enables the production of safer, more specific and reliable vaccines in a shorter amount of time.

In addition, it allows the scientists to create the vaccines without having to work directly with the infectious, pandemic strains reducing the risk of unwittingly releasing the dangerous agents into the environment.

MedImmune, bought for €11.5bn in June this year by AstraZeneca, has recently overcome "quality and compliance" problems with regards to the production of its own influenza vaccine, FluMist.