A newer version of MedImmune’s FluMist appears effective for children younger than 5 years old, although safety data on the influenza vaccine is still under review, FDA staffers wrote in documents released on the agency’s web site today.

MedImmune, which last month agreed to be bought by AstraZeneca, is seeking FDA approval to market the spray for children ages 1 to 5, without a history of wheezing or asthma. It is already approved for healthy people between 5 and 49 years old.

An FDA advisory panel meets on Wednesday to discuss whether to recommend that the agency grant wider approval. While the FDA usually follows the advice of its outside experts, it will make the final decision.

“They have to get this young children expansion, it’s quite important for the company,” says Eun Yang, an analyst at Jeffries & Co., tells Bloomberg News. Sales may rise as much as fivefold to $200 million within five years if the vaccine is approved and recommended for children under age five.

Four studies conducted by MedImmune found the drug was effective against Type A and B influenza viruses, including one trial that showed the vaccine was about 90 percent effective, according to the FDA document.

Reviewers for the FDA also said one company study of the nasal spray vaccine did not signal any widespread safety problems, but results from other studies are still being reviewed. Those findings will be presented to the panel on Wednesday.

Children who received FluMist experienced more wheezing than those who were given an inactive vaccine, but “the difference between treatment groups is quite small,” one reviewer wrote. A “small” risk of wheezing seen in study participants under age two should be weighed against the risk of hospitalization from the flu.

Regulators are expected to make a decision on approval by May 28.

Further reading:
Bloomberg News;
Reuters;
FDA and MedImmune briefing documents.[tags]FluMist, MedImmune[/tags]