Study of a Combination Vaccine Comprised of Different Recombinant Spike Antigen Levels of a Matrix-M Adjuvanted Recombinant COVID-19 Vaccine and Recombinant Influenza Vaccine in Adult Participants 50 Years of Age and Older

Inclusion Criteria: Inclusion criteria to be checked at Screening Visit: * Aged 50 years or older on the day of inclusion Informed consent * Informed consent form has been signed and dated. * Able to attend all scheduled visits and to comply with all study procedures. * Participant must be able to receive an injection in the deltoid muscle of both arms. * Participant must have completed a primary vaccination series against SARS-CoV-2 and at least 1 booster with a locally authorized or approved COVID-19 vaccine. Inclusion criteria to be checked at Visit 1 (Day \[D\]01): * Aged 50 years or older on the day of inclusions * Participants who are healthy or with pre-existing stable condition (defined as disease not requiring significant change in therapy or hospitalization for worsening disease during the 12 weeks before enrollment), as determined by medical evaluation including medical history and physical examination. * A female participant is eligible to participate if she is not pregnant or breastfeeding and one of the following conditions applies: * Is of non-childbearing potential. To be considered of non-childbearing potential, a female must be post-menopausal for at least 1 year, or surgically sterile. OR • Is of childbearing potential and agrees to use an effective contraceptive method or abstinence from at least 4 weeks prior to study intervention administration until at least 4 weeks after study intervention administration. A female participant of childbearing potential must have a negative highly sensitive pregnancy test (urine or serum as required by local regulation) on the day of enrollment before the first dose of study intervention. * Informed consent form has been signed and dated. * Able to attend all scheduled visits and to comply with all study procedures. * Participant must be able to receive an injection in the deltoid muscle of both arms. * Participant must have completed a primary vaccination series against SARS-CoV-2 and at least 1 booster with a locally authorized or approved COVID-19 vaccine. Exclusion Criteria to be checked at Screening Visit and at Visit 1 (D01): * Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (for glucocorticoids, ≥ 10 milligrams/day of prednisone or equivalent for more than 2 consecutive weeks within the past 3 months). * Known systemic hypersensitivity to any of the study intervention components, or history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances . * Self-reported thrombocytopenia, contraindicating intramuscular injection, based on investigator's judgment. * Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating intramuscular injection, based on investigator's judgment. * Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with study conduct or completion . * Any illness that, in the opinion of the investigator, would pose a health risk to the participant if enrolled. * Moderate or severe acute illness/infection (according to investigator judgment) or febrile illness (temperature ≥ 100.4°F) on the day of study intervention administration. A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided. * Alcohol, prescription drug, or substance abuse that, in the opinion of the Investigator, might interfere with the study conduct or completion. * History of serious adverse reaction to any influenza or COVID-19 vaccines. * Personal or family history of Guillain-Barré syndrome. * Prior history of myocarditis, pericarditis, or myopericarditis. * Prior history of stroke or stroke risk factors, which may include untreated/uncontrolled hypertension, hyperlipidemia, or diabetes; active smoking; obesity, based on investigator's judgment; history of thromboembolic disease; cardiac structural abnormality; atrial fibrillation; carotid stent placement; or family history of stroke. Prior/concomitant therapy * Receipt of any vaccine in the 4 weeks preceding study intervention administration or planned receipt of any vaccine prior to the second blood draw (ie, approximately in the 28 days following study intervention administration. * Previous vaccination against influenza (in the previous 6 months) with an investigational or marketed vaccine. * Previous vaccination against COVID-19 (in the previous 6 months) with an investigational or marketed vaccine OR history of COVID-19 in the previous 6 months. * Receipt of immune globulins, blood or blood-derived products in the past 3 months