WASHINGTON, D.C.--A new type of flu vaccine, delivered in a nasal spray, has produced an immune response in children in a small field trial. Researchers don't yet know whether the spray, described here today at the annual meeting of the Pediatric Academic Societies, protects kids against infection, but if it does, it could take a bite out of the transmission of flu from children to weak or elderly people.
Children usually don't get flu shots, because they ordinarily recover quickly from influenza infections. But sneezy kids can infect the weak, so pediatrician James King of the University of Maryland Medical Center set out to make a children's vaccine less painful to administer. His team mixed three common strains--H3N2, H1N1, and type B--that had been bred, or "cold-adapted," to survive in the throat and nose but die in the warmer environs of the lungs. The team gave 356 children aged 18 months to 6 years either the vaccine or a saltwater placebo. There were no side effects, and King says the kids seemed not to mind the spray: "Some cry, but most laugh or giggle."
The spray boosted the immune response against two of the strains. Blood samples taken 6 weeks after vaccination revealed a fourfold jump in antibodies to H3N2 in 90% of the kids. Half the group had a similar response to the B strain. But only 16% of vaccinated children mounted a significant response to the H1N1 strain, probably because this strain was weaker than the others.
"It's an appealing approach," says Samuel Katz, a pediatrician at Duke University. "If you can start with two out of three [strains], it's a good thing." King is now running a larger trial in which 1300 kids have received two doses of vaccine. The results of that study--which also will test whether the vaccinated kids are less likely to come down with the flu--will be available this fall.