These data demonstrate that Fluzone High-Dose vaccine provided improved protection against influenza ("the flu") compared to standard-dose Fluzone vaccine (trivalent intramuscular formulation) in adults 65 years of age and older.
The Prescribing Information for Fluzone High-Dose vaccine now includes data from a large-scale, multi-center efficacy and safety trial published in the August 14, 2014, issue of The New England Journal of Medicine (DOI: 10.1056/NEJMoa1315727).
The study found Fluzone High-Dose vaccine was 24.2 percent (95% CI, 9.7 to 36.5) more effective than standard-dose Fluzone vaccine in preventing laboratory-confirmed influenza caused by any influenza viral type or subtype in association with influenza-like illness, the primary endpoint.
This indicates that about one in four breakthrough cases of influenza could be prevented if Fluzone High-Dose vaccine were used instead of the standard-dose Fluzone vaccine in the 65 and older population.
"Inclusion of these efficacy data in the Fluzone High-Dose vaccine Prescribing Information validates the importance of this vaccine for people 65 years of age and older," said David P. Greenberg, M.D., Vice President, Scientific & Medical Affairs, and Chief Medical Officer, Sanofi Pasteur US.
"We are fully committed to helping protect patients from influenza, and we urge everyone eligible — especially older adults — to get vaccinated as soon as possible if they have not already done so."
Fluzone High-Dose vaccine is an inactivated influenza vaccine that contains four times the amount of antigen (60 mcg hemagglutinin [HA] per strain) than is contained in standard-dose Fluzone vaccine (15 mcg HA per strain). Post-vaccination, Fluzone High-Dose vaccine induces higher antibody responses compared to standard-dose Fluzone vaccine.
In response to the unmet medical need in older adults, Fluzone High-Dose vaccine was licensed by the FDA in December 2009 under the agency’s accelerated approval process. Licensure was based on the vaccine’s safety profile and superior immunogenicity compared to standard-dose Fluzone vaccine. Immunogenicity (the ability of a vaccine to trigger the body to produce antibodies against an infectious agent) is commonly used to evaluate vaccines in clinical trials.
"We look forward to further discussing these data with the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices and other health policy-makers," said Phil Hosbach, Vice President, New Products and Immunization Policy, Sanofi Pasteur.
"Given the significance of these results, we believe that Fluzone High-Dose vaccine fills a vital public health need as the only influenza vaccine shown specifically to address the age-related decline of the immune system. Compared to younger adults, people 65 years of age and older suffer disproportionately from seasonal influenza and its complications, including severe illness leading to hospitalization and death."
Adults aged 65 and older typically account for more than half (60 percent) of influenza-related hospitalizations and almost all (90 percent) of influenza-related deaths.[ii] Studies have shown people aged 65 years and older do not respond to standard-dose influenza vaccine as well as younger adults and may be left without sufficient protection,[iii] especially against influenza A/H3N2, which is considered the most burdensome in older adults.[iv][v]
This study was a multi-center, double-blind post-licensure efficacy trial conducted in the United States and Canada in which adults 65 years of age and older were randomized (1:1) to receive either Fluzone High-Dose vaccine or Fluzone vaccine. The study was conducted over two influenza seasons (2011-2012 and 2012-2013).
The study compared the efficacy and safety profiles of Fluzone High-Dose vaccine to those of Fluzone vaccine. The per-protocol analysis set for efficacy assessments included 15,892 Fluzone High-Dose vaccine recipients and 15,911 Fluzone vaccine recipients.
The primary endpoint of the study was the occurrence of laboratory-confirmed influenza (as determined by culture or polymerase chain reaction) caused by any influenza viral type/subtype in association with influenza-like illness (ILI), defined as new onset (or exacerbation) of at least one of the following respiratory symptoms: sore throat, cough, sputum production, wheezing, or difficulty breathing; concurrent with at least one of the following systemic signs or symptoms: temperature greater than 99.0 degrees F (37.2 degrees C), chills, tiredness, headaches or myalgia.
A secondary endpoint of the study was the occurrence of culture-confirmed influenza caused by viral types/subtypes antigenically similar to those contained in the vaccines in association with a modified CDC-defined ILI, defined as the occurrence of a temperature greater than 99.0 degrees F with cough or sore throat. The efficacy of Fluzone High-Dose vaccine relative to Fluzone vaccine for this endpoint was 51.1 percent (95% CI, 16.8 to 72.0).
The safety analysis set included 15,992 Fluzone High-Dose vaccine recipients and 15,991 Fluzone vaccine recipients. Within the study surveillance period (approximately six to eight months post-vaccination), 1,323 (8.3 percent) Fluzone High-Dose vaccine recipients and 1,442 (9.0 percent) Fluzone vaccine recipients experienced a serious adverse event (SAE).
Within 30 days post-vaccination, 204 (1.3 percent) Fluzone High-Dose vaccine recipients and 200 (1.3 percent) Fluzone vaccine recipients experienced an SAE. The majority of these participants had one or more chronic comorbid illnesses. A total of 167 deaths were reported within six to eight months post-vaccination: 83 (0.5 percent) among Fluzone High-Dose vaccine recipients and 84 (0.5 percent) among Fluzone vaccine recipients; no deaths were considered by the investigators to be related to vaccination.