Mismatches occur regularly between circulating influenza B viruses and vaccination strains. In a randomised, double-blind, controlled phase III clinical research, healthy children aged 6–35 months were randomly assigned to one of three groups and given two doses of quadrivalent influenza vaccinations (QIVs) or licenced trivalent influenza vaccines in a 2:1:1 ratio (TIVs). The major goal was to assess the non-inferiority immunogenicity of QIV to that of the two TIVs carrying the B/Victoria or B/Yamagata strains. Serious adverse events (SAEs) were tracked for six months following the second immunisation. This research included a total of 2146 people.

Based on hemagglutination inhibition (HI) antibodies, QIV was found to be non-inferior to TIVs for shared strains and the matching BY strain 28 days after the second dose of vaccination. The variations in seroconversion rates were 0.46 percent for H1N1, 1.95 percent for H3N2, and 3.58 percent for BY. With a GMT of 1:52.25 and a seroconversion rate of 59.49 percent, the BV strain in QIV did not meet the non-inferiority criterion. There were no elevated safety concerns in the QIV group. Candidate QIV has been shown to provide enough protection for children aged 6 to 35 months, as well as to be immunogenic and safe.

Reference: https://www.tandfonline.com/doi/full/10.1080/21645515.2020.1721994