A non-adjuvanted whole-virus H1N1 pandemic vaccine is well tolerated and highly immunogenic in children and adolescents and induces substantial immunological memory.

摘要

This phase 1/2 open-label, randomized clinical study investigated the safety and immunogenicity of a non-adjuvanted, whole virus, Vero cell-derived H1N1 pandemic influenza vaccine (A/H1N1/California/07/2009) in children and adolescents (6 months to 17 years). Subjects were stratified by age (6-11 months, 12-35 months, 3-8 years, 9-17 years) to receive two vaccinations 21 days apart of either the 3.75 g or 7.5 g dose. A booster with a licensed trivalent seasonal (2010/2011) influenza vaccine was administered one year after the first vaccination to a subgroup that had previously received the 7.5 g dose. A single vaccination with the 7.5 g dose induced high seroprotection rates in all subjects, namely: 88.0% (9-17 years); 68.0% (3-8 years); 42.9% (12-35 months); and 50.0% (6-11 months). Following a second vaccination, seroprotection rates ranged from 84.2% to 100%. GMTs after two vaccinations with the 7.5 g dose (as determined by HI) were also substantial: reaching 210.0 (9-17 years), 196.2 (3-8 years), 118.9 (12-35 months) and 99.6 (6-11 months). Antibody persistence was demonstrated at 6 months (GMTs ranging from 65.6 to 212.8 with the 7.5 g dose) and at 12 months (GMTs ranging from 33.6 to 124.1 with the 7.5 g dose) after primary vaccination. The booster vaccination induced a strong response to the A/California/07/2009 strain, reaching 100% seroprotection in all age groups, with GMTs ranging from 640.0 to 886.3. The vaccine was well tolerated, inducing low adverse reaction rates (overall fever rate: 6% after the first vaccination; 7% after the second vaccination), even in young children. These data confirm that the H1N1 whole-virus Vero cell-derived pandemic influenza vaccine is suitable for use in children and adolescents; a 2-dose primary vaccination induces a memory response in a naive population that can be effectively boosted with the A/H1N1/California/07/2009 component of a seasonal influenza vaccine.