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Full-dose quadrivalent flu vaccine shows increased efficacy in children



A full 0.5-mL dose of inactivated influenza vaccine was as safe and effective as a was a half dose of 0.25 mL, with slightly higher immunogenicity, according to data from a randomized trial of nearly 2,000 children aged 6-35 months.

A doctor vaccinates a toddler KatarzynaBialasiewicz/Thinkstock

Data from previous studies have suggested that a full dose of vaccine may be more immunogenic in young children compared with a half dose, and Sanofi Pasteur has submitted a supplemental Biologics License Application to the Food and Drug Administration to allow use of the full 0.5-mL dose in children as young as 6 months, Monica Mercer, MD, of Sanofi Pasteur, said at a meeting of the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices in Atlanta.

Dr. Mercer presented findings from a phase IV randomized, observer-blinded study, in which the researchers assigned healthy children aged 6-35 months to receive Fluzone quadrivalent vaccine at a dose of 0.25 mL or 0.5 mL.

A total of 1,941 children (949 for the 0.25-mL dose and 992 for the 0.5-mL dose) were included in the safety analysis.

The most important safety outcome was to compare the rate of any fever, Dr. Mercer said at the meeting.

Overall, at 7 days after vaccination, the rate of fever was 11% for the half dose and 12% for the full dose, she said. The resulting difference of 0.84% met the criteria for noninferiority (less than 5%), she added.

In terms of safety, tenderness was the most frequently reported injection site reaction, noted in 47% of the half-dose group and 50% of the full-dose group. The rates of unsolicited adverse events were similar in both groups, the most common included diarrhea and cough, Dr. Mercer said.

No subjects in the full-dose group and three in the half-dose group discontinued the study because of adverse events. The only reported serious adverse event was one case of chronic urticaria in the half-dose group; no deaths were reported in either group.

As for efficacy, the full dose demonstrated noninferiority, compared with the half dose, against each of four strains: influenza A H1N1, influenza A H3N2, influenza B Victoria, and influenza B Yamagata. The geometric mean titers of the full and half doses for each of the four strains were, respectively, 310 and 214, 332 and 221, 348 and 261, and 349 and 243.

The potential action date for the supplemental Biologics License Application is January 2019, noted Dr. Mercer, who is employed by Sanofi Pasteur.

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