A new nasal vaccine against influenza, which helps patients avoid the needle, has caused no unexpected side-effects, U.S. government researchers reported Tuesday.
A study of the 2.5 million people who got the vaccine over the past two flu seasons showed no unexpected serious risks, according to the report in the Journal of the American Medical Association.
FluMist has been approved since 2003 for use against the seasonal flu, which kills 36,000 Americans every year and as many as 500,000 globally in an average flu season. But people have been slow to use it, despite efforts by U.S. health officials to promote its use.
The vaccine, which is squirted up the nose using a special spray-like device, is approved for healthy people aged 5 to 49. Asthma patients are advised to avoid the vaccine in case it worsens their symptoms.
There had been some fears that it may cause unusual side effects because it must be sprayed up the nose and because it uses a live but weakened form of the influenza virus, as opposed to the injected shots, which use inactivated or ”killed” virus.
Dr. Hector Izurieta of the Food and Drug Administration and colleagues examined the adverse events reported to the U.S. Vaccine Adverse Event Reporting System during the first two seasons of the new vaccine’s use.
“Among two and a half million people who received the vaccine, we received only 460, approximately, reports of illness or problems with the vaccination -- that’s not a large number,” Izurieta said.
No cases were fatal.
“A few of them were serious allergic reaction. A few of them were asthma attacks among people who had a prior asthma history,” Izurieta said.
“Those people who had the prior asthma history should not have received the vaccine anyway.”
There were seven reports of possible anaphylaxis, which is a severe allergic reaction. There were two reports of Guillain-Barre syndrome, which is a temporary inflammation of the nerves, causing pain, weakness, and some paralysis; one report of Bell palsy, a paralysis of the facial muscles; and eight reports of worsened asthma.
These side-effects were not any more common than in people getting injected vaccine, the researchers said.
As the vaccine is live, it is possible that someone could pass the virus to a susceptible person, such as a cancer or AIDS patient. There were 22 such cases reported.
Only a few of these cases were tested to see if the virus was in fact from the vaccine, or if the patient caught circulating influenza elsewhere.
The most serious case involved a 3-yea- old girl with flu-like symptoms who developed pneumonia three days after her mother got the FluMist vaccine -- but it was unclear if the vaccine was the cause of the girl’s illness. She recovered.
Last year the United States lost half its anticipated flu vaccine supply when maker Chiron Corp. had contamination and lost its license. Sanofi-pasteur and GlaxoSmithKline also make standard injected vaccines for the U.S. market.
This year nearly 90 million doses are expected for the U.S. market, but just 1 million FluMist doses. Like the injected vaccine, FluMist provides no protection against the H5N1 avian flu -- only against seasonal flu.