GlaxoSmithKline has received a boost from regulators in the USA who have given the green light to the UK drug major's influenza vaccine Fluarix Quadrivalent.

The Food and Drug Administration has approved the latter for the immunisation of children over three and adults to help prevent disease caused by seasonal flu virus subtypes A and type B contained in the vaccine. Fluarix Quadrivalent is the first intramuscular vaccine to cover against four influenza strains.

GSK noted that currently-administered trivalent flu vaccines help protect against the two A virus strains most common in humans and the B strain expected to be predominant in a given year. However, since 2000, two B virus strains (called Victoria and Yamagata) "have co-circulated to varying degrees each season".

The company goes on to say that "various degrees of mismatch have occurred between the B strain included in trivalent vaccines and the B strain that actually circulated". This has caused an increased risk of influenza-related morbidity "across all age groups".

Leonard Friedland, head of GSK North America vaccines clinical development and medical affairs, noted that trivalent vaccines "have helped protect millions of people against flu, but in six of the last 11 flu seasons, the predominant circulating influenza B strain was not the strain that public health authorities selected". Given that Fluarix Quadrivalent will protect against both B strains, "from a public-health standpoint, [it] can help decrease the burden of disease".

GSK added that it will make Fluarix Quadrivalent available in time for the 2013-14 flu season and and also plans to fulfill orders for its trivalent vaccines. Healthcare providers traditionally order their vaccines about a year in advance of each flu season.

In February this year, the FDA approved the first four-strain flu vaccine, FluMist Quadrivalent from AstraZeneca's MedImmune unit.