In children 6 through 47 months of age, cell-based quadrivalent inactivated influenza vaccine (QIVc) was well tolerated and produced immune responses similar those of a U.S.-licensed quadrivalent inactivated influenza vaccine (QIV), according to results of a phase 3 noninferiority trial. “This vaccine represents a viable option for vaccination in the pediatric population,” the investigators conclude.
Conducted during the Northern Hemisphere 2019–2020 influenza season, participants randomly received 1 or 2 doses of QIVc or QIV. Efficacy was evaluated using antibody titers at 28 days, and safety data were collected for 180 days after the last vaccination. Noninferiority criteria included a geometric mean titer ratio (QIV:QIVc) of 1.5 for the upper bounds of the 2-sided 95% confidence interval (CI) and less than a 10% difference in seroconversion rates.
Results showed: “Immunogenicity was evaluated in 1092 QIVc and 575 QIV subjects. Success criteria were met for all vaccine strains. Geometric mean titer ratios (upper bound 95% CI) were A/H1N1, 0.73 (0.84); A/H3N2, 1.04 (1.16); B/Yamagata, 0.73 (0.81); and B/Victoria, 0.88 (0.97). Seroconversion differences (upper bound 95% CI) were −11.46% (−6.42), 3.13% (7.81), −14.87% (−9.98), and −5.96% (−1.44) for A/H1N1, A/H3N2, B/Yamagata, and B/Victoria, respectively. Rates of adverse events were similar between the 2 groups with no serious adverse events related to vaccination.”
Editorial: “Although QIVc will still focus the immune response on single antigenic variants and require accurate prediction of circulating strains for effectiveness, this vaccine utilizes a widely available, egg-sparing platform that minimizes adaptation of candidate vaccine strains,” editorialists write. “The availability of QIVc for the youngest of children thus has potential to direct early life influenza immunity toward clinically relevant epitopes, avoiding development of anti-influenza immune memory against undesirable epitopes only present in egg-adapted viruses. By demonstrating the safety and immunogenicity of cell-based vaccines in young children, [this] manuscript … represents an important advancement for pediatric influenza vaccines.”