A high-dose recombinant influenza vaccine is more effective than standard-dose vaccine among adults aged 50 to 64 years, according to a study published in the Dec. 14 issue of the New England Journal of Medicine.
Amber Hsiao, Ph.D., M.P.H., from the Kaiser Permanente Vaccine Study Center in Oakland, California, and colleagues conducted a cluster-randomized observational study to compare the effectiveness of recombinant vaccines as compared with standard-dose vaccines against influenza-related outcomes in adults under the age of 65 years. During the 2018 to 2019 and 2019 to 2020 influenza seasons, facilities routinely administered either a high-dose recombinant influenza vaccine (Flublok Quadrivalent) or one of two standard-dose influenza vaccines to adults aged 50 to 64 years and 18 to 49 years.
Data were included for 1,630,328 individuals aged 18 to 64 years who received vaccines (632,962 in the recombinant-vaccine group and 997,366 in the standard-dose group). The researchers identified 1,386 and 2,435 cases of polymerase chain reaction (PCR)-confirmed influenza diagnosed in the recombinant-vaccine and standard-dose groups, respectively. Among participants aged 50 to 64 years, 2.00 and 2.34 cases per 1,000 tested positive for influenza in the recombinant-vaccine and standard-dose groups, respectively (relative vaccine effectiveness, 15.3 percent). The relative vaccine effectiveness against influenza A was 15.7 percent in the same age group. Compared with the standard-dose vaccines, the recombinant vaccine was not significantly more protective against influenza-related hospitalization.
