Fluzone High-Dose Quadrivalent

Influenza illness and its complications like primary viral or secondary bacterial pneumonia, serious cardiac events, and neurologic complications as well as exacerbation of underlying conditions like congestive heart failure, chronic obstructive pulmonary disease (COPD), asthma, and diabetes follow infection with influenza viruses. Global surveillance of influenza identifies yearly antigenic variants. For example, since 1977, antigenic variants of influenza A (H1N1 and H3N2) viruses and influenza B viruses have been in global circulation. Specific levels of hemagglutination inhibition (HAI) antibody titre post-vaccination with inactivated influenza virus vaccines have not been correlated with protection from influenza virus infection.Antibodies against one influenza virus type or subtype confer limited or no protection against another. Furthermore, antibodies to one antigenic variant of influenza virus might not protect against a new antigenic variant of the same type or subtype. Frequent development of antigenic variants through antigenic drift is the virological basis for seasonal epidemics and the reason for the usual change of one or more strains in each year's influenza vaccine. Therefore, influenza vaccines are standardised to contain the hemagglutinins of influenza virus strains representing the influenza viruses likely to be circulating in the upcoming season.Annual influenza vaccination is recommended because immunity during the year after vaccination declines and because circulating strains of influenza virus change from year to year.The indication of Fluzone High-Dose Quadrivalent is based on the demonstration of non-inferior immunogenicity between Fluzone High-Dose Quadrivalent and Fluzone High-Dose (inactivated trivalent influenza vaccine, TIV-HD) which allows the efficacy of Fluzone High-Dose Quadrivalent to be inferred from that for TIV-HD. Similarly, the effectiveness for Fluzone High-Dose Quadrivalent can also be inferred from the data generated for TIV-HD.Thus, Fluzone High-Dose Quadrivalent is inferred to be more effective in preventing influenza and its complications, compared to standard dose inactivated influenza vaccine (15 µg of each of the strains) in adults 65 years of age and older.