UPDATE 1-EU backs first pre-pandemic flu shot from Glaxo

(Adds Glaxo reaction, quote, background)

LONDON, Feb 21 (Reuters) - The European Medicines Agency has recommended approval of the first pre-pandemic influenza vaccine, Prepandrix, from GlaxoSmithKline Plc GSK.L, the London-based watchdog said on Thursday.

The shot is intended for use before a pandemic or during an officially declared flu pandemic. It is designed to trigger an immune response against the H5N1 strain of bird flu, which experts fear may become the spark for a flu outbreak threatening millions of people.

Recommendations for marketing approval by the agency’s Committee for Medicinal Products for Human Use (CHMP) are normally endorsed by the European Commission within a couple of months.

The green light from the committee puts Europe’s biggest drugmaker ahead of rivals in the race to win a licence for its vaccine, which several governments around the world have already said they plan to stockpile.

“It reflects the growing recognition of pre-pandemic vaccination as an important strategy for addressing the current pandemic threat posed by H5N1,” said Glaxo’s head of vaccine Jean Stephenne.

Other companies including Sanofi-Aventis SASY.PA and Novartis AG NOVN.VX are also working on bird flu vaccines and industry analysts say such products may represent a $1 billion-plus sales opportunity.

Glaxo’s vaccine should give a degree of protection until a more precisely tailored pandemic vaccine can be produced -- a process likely to take four to six months from the time any pandemic strain is identified.

The new vaccine contains a special additive, or adjuvant, which allows a very low dose of active ingredient to be used in each shot.

A key challenge in producing a vaccine for millions of people around the world is how to make the maximum number of shots from the minimum amount of antigen, or active ingredient. While H5N1 remains mainly a virus affecting birds, scientists say it is the most likely source of the next global flu pandemic in humans, since it may soon mutate into a form transmitted easily from person to person. (Reporting by Ben Hirschler; Editing by Rory Channing)