Children aged 2 to 18 years can get either the injected trivalent inactivated influenza vaccine (TIV) or the live attenuated influenza vaccine (LAIV), given in the form of a nasal spray. Children under 2 should get only TIV, he added.
"Previous research has shown that the TIV does not provoke asthma attacks, but we've yet to see how effective it is in reducing hospitalization rates associated with the seasonal flu," Joshi said.
The authors looked back at 263 children aged 6 months to 18 years who had visited the Mayo Clinic between 1999 and 2006 with laboratory-confirmed influenza.
Children -- including children who had asthma -- who received the annual inactivated flu vaccine were almost three times more likely to be hospitalized than those who were not inoculated.
There is no reason to believe the vaccine actually caused the hospitalizations, Joshi emphasized. This could simply mean that the shot isn't effective in preventing hospital stays.
"The flu shot may be safer in terms of triggering a wheezing episode, but we don't know how effective it is. We need more studies to assess the effectiveness of different kinds of vaccines. There could be something that has higher efficacy not only in preventing influenza illness, but also hospitalizations," she said.
"Vaccination should be universal, but we may need to find more effective vaccines," Joshi added. "This is a good vaccine. We could have better."
Here are the U.S. Centers for Disease Control and Prevention's recommendations for the flu vaccine in children.
SOURCES: Avni Y. Joshi, M.D., fellow, allergy, immunology and infectious diseases, Mayo Clinic, Rochester, Minn.; Gurjit Khurana Hershey, M.D., Ph.D., director, Divisi
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