One Dose of H1N1 Vaccine May Be Enough for Children
A single dose of vaccine may be sufficient to protect most infants and children against 2009 H1N1 influenza, according to a JAMA study released online, but editorialists say the data are not compelling enough to change the current U.S. recommendation for two doses for younger patients.
Australian researchers, including some from the vaccine manufacturer, randomized roughly 350 children between ages 6 months and 9 years to a two-dose regimen of 15 µg or 30 µg of intramuscular monovalent vaccine. After the first dose in the 15-µg group, more than 92% had titers of 1:40 or higher — levels generally considered protective. The prevalence of protective titers was even higher in the 30-µg group. After the second dose, all children showed protective titers.
Editorialists say that “at least some children” will be protected with a single dose, “but the findings cannot be generalized with confidence.” Given the study’s limitations, they conclude that “it remains prudent to continue to follow current recommendations” for two doses.