Safety and immunogenicity of two subunit influenza vaccines in healthy children, adults and the elderly: a randomized controlled trial in China.

ABSTRACT

The burden of influenza is well known in the elderly and at-risk patients, but also in children. Especially in those under 5 years old, influenza may cause severe morbidity and mortality. Influenza infections and complications can be reduced by vaccination. In a randomized, endpoint-blinded, parallel group trial the immunogenicity and safety was studied of two trivalent inactivated surface antigen (subunit) influenza vaccines Influvac and Agrippal in healthy children as well as in adults and the elderly. An open safety part in 30 children aged 3-12 years and 30 adults aged 18-60 years vaccinated with Influvac was followed by an endpoint-blind, parallel group part in 300 healthy children aged 3-12 years, 300 healthy adults aged 18-59 years, and 240 healthy elderly persons aged 60 years or over, in which subjects were randomized 21 to vaccination with either Influvac or Agrippal. The primary immunogenicity endpoint was the geometric mean titer (GMT) 4 weeks after vaccination. Both Influvac and Agrippal induced high anti-hemagglutinin antibody titers in the children and in the adult and elderly subjects. Seroprotection rates were >85% and seroconversion rates >70% for both vaccines in all three age groups for all three-virus strains. The GMT ratios after vaccination indicated that the immunogenicity of Influvac was at least comparable with that of Agrippal in all three age groups. Both vaccines were well tolerated and safe. In this trial, Influvac and Agrippal were immunogenic, safe and well tolerated in healthy children as well as in adults and elderly people.