The clinical trial in children evaluated immune responses to Sanofi Pasteur's Influenza A (H1N1) 2009 Monovalent Vaccine compared with placebo, based on rates of seroprotection and seroconversion. Two doses of vaccine were administered, the second dose 21 days after the first. Immunogenicity was measured at day 21, just prior to administration of the second dose, and will be measured again 21 days after the second dose at day 42. In both age groups, immune responses 21 days after one dose of the 15 mcg vaccine satisfied the criteria for seroconversion. The criteria for seroprotection were not met with only one 15 mcg dose of vaccine in either age group. In this clinical trial 76 percent of children 3 years through 9 years of age and 50 percent of children 6 months through 35 months of age had immune responses considered seroprotective following one 15 mcg dose of vaccine. An antibody titer of 1:40 or greater is generally considered a marker of seroprotection. A lower rise in antibody titers following vaccination may minimize the occurrence of disease and its consequences but is not considered seroprotective. Final data from these clinical trials, following a second dose of vaccine, will provide additional information to guide recommendations on the optimal dosage, number of doses and schedule.

Adverse events are being monitored throughout the clinical trial and will continue for six months after the second dose of vaccine. No serious adverse events have been reported in the trial to date. Local reactions reported have been similar to those observed with the seasonal influenza vaccine.

SOURCE Sanofi Pasteur