Cell-derived flu vaccine noninferior to egg-based vaccine in children, study finds
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The results of a phase 3 trial demonstrated that a cell-derived quadrivalent influenza vaccine was well tolerated and elicited noninferior antibody responses compared with a licensed quadrivalent egg-based vaccine in young U.S. children.
Results of the trial were presented during the virtual Annual Conference on Vaccinology Research sponsored by the National Foundation for Infectious Diseases.
In the study, Marten Heeringa, PhD, senior clinical program scientific lead at Seqirus, and colleagues randomly assigned 2,414 children aged 6 to 47 months in a 2-to-1 ratio to receive either the cell-derived quadrivalent influenza vaccine (QIVc) or the licensed quadrivalent influenza vaccine (QIV). Based on vaccination history, children received either one or two doses, 28 days a part, and were followed for at least 180 days.
“Noninferiority of QIVc compared to QIV was concluded if the upper bound of the two-sided 95% confidence interval for the postvaccination [geometric mean titers] ratio did not exceed 1.5, and if the [seroconversion rate] difference did not exceed 10% for each of the four strains,” the researchers explained in the abstract.
Noninferiority was met for the geometric meant titers ratio and the seroconversion rate for each of the four influenza strains, Heeringa and colleagues reported.
“Geometric mean fold rises of pre- to post-vaccination titers for QIVc by hemagglutination inhibition assays were [more than] fourfold for [influenza] A/H1N1, A/H3N2, and B/Yamagata and 2.65 for B/Victoria,” they wrote.
Solicited adverse events were reported in 64% of participants who received QIVc, and 66% of participants in the QIV arm. The most common reported adverse events, respectively, among both QIVc and QIV groups were tenderness (28% and 30%), erythema at the injection site (26% and 25%), irritability (28% and 30%) and sleepiness (27% and 26%).
Fever was reported in less than 7% of all participants. Additionally, the rate of serious adverse events was less than 1% for both groups, the researchers reported.