Immunogenicity, reactogenicity and safety of an inactivated quadrivalent influenza vaccine in children and adolescents 6 months through 17 years of age in India.

Efficacy and safety data on quadrivalent influenza vaccines (QIVs) for immunization of Indian children are scarce. This phase 3, registration study evaluated the immunogenicity, safety, and tolerability of a QIV in Indian children aged 6-35 months (Group 1) and 3-17 y (Group 2). Subjects received one or two doses (0.5 mL each) of the study vaccine based on their priming status. Immunogenicity (post-vaccination geometric mean fold increase in hemagglutination inhibition [HI] titers and proportion of patients with seroprotection and seroconversion against the four influenza strains), unsolicited adverse events (AEs), and tolerability were analyzed. Among 118 subjects enrolled in each group, the geometric mean(standard deviation) fold increase in HI titers against A(H3N2), A(H1N1), B(Victoria), and B(Yamagata) strains were 31.7(5.33), 10.5(6.06), 4.1(5.70), and 8.6(5.34) in Group 1 and 14.0(4.37), 9.2(4.26), 14.3(6.73), and 14.4(5.41) in Group 2, respectively. Seroprotection was achieved by 91.2%, 83.3%, 41.2%, and 68.4% subjects in Group 1 and 100%, 95.8%, 73.7%, and 89.8% subjects in Group 2, respectively. Seroconversion was achieved by 87.7%, 66.7%, 41.2%, and 64.9% subjects in Group 1 and 89.0%, 78.8%, 69.5%, and 75.4% subjects in Group 2, respectively. Vaccination site pain and fever were the most common local and systemic reactions, respectively. Systemic reactions were more frequent in Group 1 (16.9% vs 7.6%). Most subjects (>90%) did not experience inconvenience within 7 d of vaccination; <10% in both groups reported unsolicited AEs. Thus, the QIV had a positive benefit/risk profile in Indian children/adolescents aged 6 months to 17 y.