A Study to Assess the Safety and Immune Response of a Vaccine Against Influenza in Healthy Younger and Older Adults

Inclusion Criteria

• A male or female between and including 18 and 50 years of age in Phase 1 and between and including 18 and 85 years of age (YA: 18-64; OA: 65-85) in Phase 2 at the time of the study intervention administration.
• Healthy participants or medically stable participants as established by medical history, clinical examination, and safety laboratory assessments. Participants with chronic medical conditions with or without specific treatment are allowed to participate in this study if considered by the investigator as medically stable. A stable medical condition is defined as disease not requiring significant change in therapy or hospitalization for worsening disease during 3 months before enrollment.
• Body mass index (BMI) >=18 kilograms per meter square (kg/m^2) and less than or equal to ( 5 years.
• Any confirmed or suspected immunosuppressive or immunodeficient condition, including HIV infection, based on medical history and physical examination (no laboratory testing required). However, in Phase 2, HIV-infected individuals may be enrolled if participants have been stable on antiretroviral therapy for the past 6 consecutive months, i.e., their treatment has not been modified, their cluster of differentiation 4 (CD4) cell count is >=200/cubic millimeter (mm^3) and their viral load has been undetectable (i.e., HIV-RNA less than ( =20 milligrams (mg)/day. Inhaled, topical and intraarticular steroids are allowed.

Other exclusions

• Concurrently participating in another clinical study, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational intervention (drug/invasive medical device).
• Pregnant or lactating female.
• Bedridden participants.
• Female planning to become pregnant or planning to discontinue contraceptive precautions within the 1-month post-dosing period.
• Alcoholism or substance use disorder within the past 24 months based on the presence of 2 or more of the following abuse criteria: hazardous use, social/interpersonal problems related to use, neglect of major roles to use, withdrawal, tolerance, use of larger amounts or longer, repeated attempts to quit or control use, much time spent using, physical or psychological problems related to use, activities given up to use, craving.
• Any study personnel or their immediate dependents, family, or household members.
• Participants with extensive tattoos covering deltoid region on both arms that would preclude the assessment of local reactogenicity.