Sanofi Pasteur Reports Results Of Clinical Trials Of Influenza A Vaccine

Sanofi Pasteur has reported the interim analysis of data from clinical trials of the US licensed Influenza A (H1N1) 2009 Monovalent Vaccine in infants and children 6 months through 9 years of age. The data indicate that the vaccine is immunogenic and that one dose may protect many children.

However, the study suggests that two doses of vaccine will be required for optimal protection of children under the age of 10 years. This is consistent with the recommendations for seasonal influenza immunisation in children of this age. Clinical trials are ongoing to evaluate the immunogenicity and safety in children following two doses of vaccine.

Reportedly, the company has conducted this randomised, placebo-controlled, multicenter trial to determine the immunogenicity and safety of the vaccine, given as a two-dose schedule, 21 days apart. A total of 474 children were enrolled in the trial in two age cohorts: 229 children 6 months through 35 months of age; and 245 children 3 years through 9 years of age. The trial evaluated two antigen doses: formulated as 7.5 mcg and 15 mcg hemagglutinin in each cohort. The interim results are the first data available from children under the age of 10 years. Previously, Sanofi Pasteur had reported that 98% of adults 18 years through 64 years of age had an immune response considered protective following one 15 mcg dose of vaccine.

The company has claimed that 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 would 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.

According to the company, the criteria for seroprotection were not met with only one 15 mcg dose of vaccine in either age group. In this clinical trial 76% of children 3 years through 9 years of age and 50% of children 6 months through 35 months of age had immune responses considered seroprotective following one 15 mcg dose of vaccine. Final data from these clinical trials, following a second dose of vaccine, are expected to provide additional information to guide recommendations on the optimal dosage, number of doses and schedule.

Moreover, adverse events are also being monitored throughout the clinical trial and are expected to continue for six months after the second dose of vaccine. No serious adverse events had been reported in the trial to date.

Wayne Pisano, president and CEO of Sanofi Pasteur, said: “According to the Centers for Disease Control and Prevention young children are among those of highest priority for immunisation with the Influenza A (H1N1) 2009 Monovalent Vaccine, given the relatively high disease incidence and potential for transmission in this population. As the company licensed in the US to produce a pediatric influenza vaccine which is licensed for children as young as 6 months of age, it was the priority for Sanofi Pasteur to conduct clinical trials to evaluate the safety and immunogenicity of the pandemic vaccine in children to support decisions on vaccine administration.”