A flu spray made by Gaithersburg-based MedImmune Inc. is effective for young children, the Food and Drug Administration said yesterday, signaling that the company might soon win approval to market the vaccine for use in children younger than 5.
Some health experts say FluMist would be a welcome tool in combating the flu because it would help immunize children who could otherwise get the illness and spread it to others. An FDA advisory panel will take up the issue tomorrow, with the expectation that the agency will make a decision before the end of May.
Approval could greatly increase sales of the nasal spray vaccine by MedImmune, which agreed last month to be purchased by London-based AstraZeneca PLC for $15.6 billion. The FDA approved FluMist in 2003 but limited its use to healthy people ages 5 to 49 because of studies that linked the spray to wheezing problems among some youngsters.
The company asked the FDA last summer for approval to market FluMist for use in children ages 1 to 4 with no history of wheezing or asthma, citing more recent studies to support its request.
In a report posted yesterday on the agency's Web site, FDA experts said the wheezing incidents identified in a series of five studies were not major problems.
Children younger than 2 given FluMist were more likely to wheeze than children given shots, but the differences were "small" and the spray was effective in preventing flu, the report said. There were no drug-related deaths, admissions to intensive-care units or patients requiring ventilators, the report said.
"The data do not suggest a clinically significant safety signal for wheezing," the report said.
Company officials declined to comment on the FDA report. "We're very much looking forward to the meeting and responding to any issues raised by the FDA at [tomorrow's] session," said Karen Lancaster, a MedImmune spokeswoman.
Some experts say the language in the FDA report bodes well for MedImmune's request.
"The advisory panel may have their own questions, but I think most people believe it probably will be approved," said Dr. John Treanor, a vaccine expert at the University of Rochester School of Medicine who was not involved in the MedImmune studies.
Influenza kills about 36,000 Americans each year and causes an additional 200,000 to be hospitalized, according to the federal Centers for Disease Control and Prevention. Hospitalization and death rates are highest among young children and the elderly, experts say.
The FDA's decision to limit FluMist for use in 5- to 49-year- olds crippled its potential market because each flu season the emphasis is on vaccinating the elderly and young children, experts say.
"There are people in that age group who may want and get shots, but for the most part they aren't among what's considered high-risk groups," said Dr. James Campbell, a pediatric infectious disease specialist at the University of Maryland School of Medicine's Center for Vaccine Development.
Campbell and other vaccine experts said a nasal spray would be an effective tool in preventing flu, in part because it would mean one less needle stick for children and adults who get it. For every child vaccinated, it means one less carrier, they said.
"Folks should understand the public health implications of flu vaccination. You're not only protecting the child but those in contact with the child," said Dr. Dan Levy, an Owings Mills pediatrician and president of the Maryland Chapter of the American Academy of Pediatrics.
Flu shots use killed virus with antigens that trigger the immune system, while FluMist uses a weakened version of live flu virus that fires up the immune system in nasal and respiratory cavities, where the infection usually starts, experts say.
A long-term goal for vaccines is finding needle-free methods of delivery, Campbell said.
"So many childhood vaccines are shots. If a new vaccine comes along that isn't a shot, that would help," Campbell said. "I think it does add a tool."
Flu shots are less effective for young children than for adults, but young children remain highly susceptible to flu, Treanor said.
"That's a very important target group," he said. "Development of FluMist vaccine for young children is a major advance in controlling flu. For young children, it's clearly a better alternative."
FDA approval would open up the market for FluMist to 14 million children, company officials have said.
That could have a significant impact on sales, said Chris Connor, senior research analyst with Health Industry Insights in Framingham, Mass. Because the vaccine is inhaled and not injected, FluMist could be widely distributed to day care centers, preschools and elementary schools.
"It's a big component of why MedImmune was purchased by AstraZeneca," Connor said.
Last year, FluMist generated $36 million in sales, representing about 3 percent of the company's overall revenue, up from $21 million in 2005. Shares of MedImmune rose 2 cents yesterday, to $57.02. AstraZeneca dropped 9 cents, to $53.18.
MedImmune also hopes to win approval to distribute the vaccine to adults 50 and older but is still collecting the necessary safety data for the FDA.
"The focus right now is on pediatrics," Lancaster said.
Sun reporter Allison Connolly contributed to this article.
The U.S. Food and Drug Administration posted a report yesterday on its Web site stating that FluMist:
is effective in preventing flu among young children
causes some wheezing in those 6 months to 23 months
did not cause deaths or result in admissions to intensive care units