AstraZeneca has been boosted by the news that US regulators have given the go-ahead for FluMist, which comes from its MedImmune subsidiary, to be used as an influenza vaccine for children from two to five years of age.

FluMist, an intransal spray, is now approved for active immunisation for the prevention of disease caused by influenza A and B viruses in people from two to 49 years, and AstraZeneca noted that previously only one manufacturer had been licensed in the USA to produce a flu jab for children under four, and that is Sanofi-Aventis’ Fluzone.

The US Food and Drug Administration has based its approval on a pivotal study that included more than 4,000 children between two and five during the 2004-2005 influenza season and showed that there was a 54% reduction in cases of flu in children who received needle-free FluMist compared with those who received the traditional flu shot.

Getting this wider approval is indeed great news for AstraZeneca but it was tempered slightly by the FDA’s decision not to approve FluMist for children aged two and under due to an increased risk of hospitalisation and wheezing that was observed in clinical trials. Also it cannot be given to people over 49, comfortably the largest subgroup of patients who receive the flu jab, though MedImmune has previously said it will try for that approval at a latter date.

These points did not diminish the firm’s enthusiasm, however, and James Young, president of R&D for MedImmune, said that with the new, refrigerated formulation of the vaccine approved in January, positive results from a head-to-head study published in the February issue of the New England Journal of Medicine, plus this expanded age indication, “it is an exciting time for FluMist.”

The vaccine has had tough time on the market since it was first approved in 2003, though this was due partly to the fact that it was difficult to distribute in its original frozen form, a problem which has now disappeared with the aforementioned approval for the new spray can, which only needs to be refrigerated.

AstraZeneca has also resolved the problems highlighted in an FDA warning letter regarding “serious deviations from current good manufacturing practice” at the firm’s manufacturing plant in Liverpool, UK.