There are two vaccines currently approved for use in adults age 65 and greater: a high-dose (HD) influenza vaccine (Fluzone High-Dose) that contains 4 times the hemagglutinin dose found in the standard vaccine, and a standard-dose (SD) vaccine containing the proprietary MF59 adjuvant (Fluad). Both vaccines give significantly highly antibody responses to influenza in older adults. This study will directly compare the HD and SD vaccines in nursing home residents, the population of older adults most vulnerable to influenza outbreaks and morbidity and mortality. It will comprehensively study the innate and adaptive response to vaccination, as well as elucidate transcriptomic and proteomic signatures of vaccine response.~This is a randomized, open label study comparing the two vaccines currently approved for use in adults age ≥ 65 years: the high-dose influenza vaccine and the MF59 adjuvanted standard-dose vaccine, both quadrivalent. The young group will be comprised of individuals 21-30 years of age, and the older cohorts will consist of nursing home residents ≥65 years. Participants will also be evaluated for evidence of influenza-like illness (ILI). ILI is defined to include clinical presentation in older adults: by the presence of either two respiratory symptoms (cough, sore throat, shortness of breath, and nasal stuffiness) or one respiratory and one systemic symptom (headache, malaise, temperature >99° F, report of feverishness and muscle aches, or altered mental status). Diagnoses of influenza will be confirmed using a real-time polymerase chain reaction (PCR) test on a nasopharyngeal (NP) swab specimen done by the hospital Virology Laboratory and facilitated by the participating medical directors.~Although this is neither an efficacy or effectiveness study, participants will be randomized 1:1 to either the high-dose influenza vaccine or the MF59 vaccine within age strata. This will ensure a non-biased allocation of the two vaccines and attempts to balance participant characteristics within age strata.
This study will compare the immune response signatures (including immunologic, transcriptomic and metabolomic) of the two influenza vaccines approved for use in adults age 65 and over (Fluad and Fluzone High-Dose).