US experts to weigh Sanofi bird flu vaccine

WASHINGTON, Feb 27 (Reuters) A panel of experts will meet today to consider whether the Food and Drug Administration should approve Sanofi-Aventis' experimental bird flu vaccine, which could become the first such product cleared for the US market.

The FDA panel of outside experts will review data from both agency staff and the company before deciding whether the vaccine is safe and effective enough to protect people against the potentially pandemic H5N1 strain of the influenza virus.

While the agency has the final say, it usually follows the advice of its outside advisers.

In documents released on Monday, FDA staff said data for Sanofi's vaccine showed higher doses worked better but that it was unclear whether those results prove the product's effectiveness.

The staff also said studies of the vaccine, which targets the potentially pandemic H5N1 strain of the influenza virus, showed ''no significant safety signals.'' While the H5N1 virus so far affects mostly birds, it sometimes infects humans. But scientists fear it might mutate just enough to spread easily among people, unleashing a pandemic that could kill tens of millions of people.

So far, 274 people worldwide have been infected with the virus since 2003 and 167 of them have died, according to the World Health Organization. No cases were in the United States.

In separate documents, Sanofi said its vaccine would be a key part of the US strategy to cope with widespread infection.

In a study of 452 healthy adults ages 18 to 64, National Institutes of Health researchers found the vaccine was well tolerated and generated an immune response ''typically associated with protection against influenza,'' the company said. Any side effects were mild and temporary, it added.

Sanofi also developed a plan to monitor for possible side effects of the vaccine with routine use and in case of wider use with a pandemic.

FDA staff said the agency had not yet decided how such monitoring might differ during a outbreak.

''In addition, FDA notes that Sanofi Pasteur recommends that epidemiological studies of safety and efficacy be conducted but does not volunteer what role they might play in such studies,'' they added.

Governments of several countries, including the United States, have already given Sanofi and its rivals multimillion dollar contracts to buy bird flu vaccines for national stockpiles.

Competitors include Novartis AG and GlaxoSmithKline Plc, but Sanofi is the first to file for U.S. approval, the FDA said.

Unlike Roche Holding AG's and Gilead Sciences Inc's Tamiflu and Glaxo's Relenza, two drugs that can treat H5N1 and regular seasonal flu after infection, vaccines target the immune system in ways to prevent infection or reduce its severity.

Still, it is not clear if the vaccines under development now could protect against H5N1 if it were mutate.

Later today, FDA's advisers also plan to discuss the development of influenza vaccines for use before a pandemic arises, including what scientific data would be needed to support early vaccinations.

There is some evidence that the current H5N1 vaccines might prepare a person's immune system, improving the effects of a second dose of vaccine formulated to better match a circulating pandemic.

Sanofi stock was slightly lower at 43.81 dollars per share in afternoon trading on the New York Stock Exchange. Shares of Glaxo shares were marginally lower at 56.85 dollars while Novartis shares were down 2.8 per cent at 57 dollars , also on the NYSE.

REUTERS SBA RN0625