Medical Research: What are the main findings of the study?
Dr. Greenberg: The New England Journal of Medicine published positive results from a randomized, double-blind, large-scale, multi-center efficacy trial, which found that Fluzone® High-Dose (Influenza Vaccine) was more efficacious in preventing influenza illness (“the flu”) in adults 65 years of age and older compared to standard-dose Fluzone vaccine. Fluzone High-Dose vaccine was found to be 24.2 percent (95% CI, 9.7 to 36.5) more effective in preventing influenza relative to standard-dose Fluzone vaccine for the primary endpoint (laboratory-confirmed influenza associated with typical clinical symptoms occurring at least 14 days post-vaccination caused by any viral type or subtype). In other words, investigators determined that participants in the Fluzone High-Dose vaccine group were less likely to get the flu than those in the standard-dose Fluzone vaccine group. The study safety data were consistent with previous Fluzone High-Dose vaccine studies.
Medical Research: Were any of the findings unexpected?
Dr. Greenberg: No. In fact, the significantly improved protection against influenza illness, as demonstrated in this study, confirmed what was expected based on previous studies showing higher immune responses with Fluzone High-Dose vaccine compared to standard-dose Fluzone vaccine.
Medical Research: What should clinicians and patients take away from your report?
Dr. Greenberg: People 65 years of age and older suffer disproportionately from seasonal influenza and its complications, including severe illness, hospitalization, and death. Older adults typically do not respond as well to influenza vaccines as younger individuals because the immune system naturally weakens with age. This study found that Fluzone High-Dose vaccine was 24.2 percent (95% CI, 9.7 to 36.5) more effective in preventing influenza relative to standard-dose Fluzone vaccine, indicating that about one in four breakthrough cases of influenza illness could be prevented if Fluzone High-Dose vaccine were used instead of the standard-dose Fluzone vaccine in the 65 and over population.
We believe that the demonstrated clinical benefit will certainly translate into benefits to public health. Influenza vaccines have been shown to offer public health benefits in preventing influenza and its complications in all age groups. This prospective, randomized study provides important confirmations of the benefits of influenza vaccination.
Of note, the Centers for Disease Control and Prevention (CDC) recommends that immunization ideally should occur prior to the start of the influenza season as soon as vaccine is available for the season.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Greenberg: Researchers in this study also determined that most rates for pneumonia, cardio-respiratory conditions, hospitalizations, non-routine medical office visits, and medication use were lower for the Fluzone High-Dose vaccine group compared to the Fluzone vaccine group. Further research is warranted to evaluate these additional potential benefits of Fluzone High-Dose vaccine.
Additionally, several modeling studies presented at national and international scientific meetings have reported the cost-effectiveness of the vaccine and its favorable impact on relevant public health outcomes. Sanofi Pasteur is performing an analysis using actual numbers provided by the study to estimate the cost-effectiveness of the vaccine and its potential impact on public health.
Efficacy of High-Dose versus Standard-Dose Influenza Vaccine in Older Adults