Inclusion Criteria:  Participants who in the opinion of the investigator, can and who will comply with the requirements of the protocol (e.g., completion of the eDiaries, return for follow-up visits). Written informed consent obtained from the participant prior to performance of any study-specific procedure.  Age at study entry:  For HZ/su and mRNA-1273 booster cohort: A male or female aged 50 years or older at the time of randomization. For Flu D-QIV and mRNA-1273 booster cohort: A male or female aged 18 years or older at the time of enrollment. Healthy participants or medically stable patients as established by medical history and clinical examination at screening. A stable medical condition is defined as disease not requiring significant change in therapy or hospitalization for worsening disease during the 3 months before enrolment. Participants who have a documented previous mRNA-1273 primary vaccination series completed (i.e., both doses) at least 6 months prior to first vaccination. Female participants of non-childbearing potential may be enrolled in the study. Non-childbearing potential is defined as pre-menarche, current bilateral tubal ligation or occlusion, documented total hysterectomy, bilateral ovariectomy, or bilateral salpingectomy, or post-menopause.  Female participants of childbearing potential may be enrolled in the study, if the participant:  Has practiced effective contraception for 1 month prior to study intervention administration, and Has a negative pregnancy test on the day of study intervention administration, and Has agreed to continue effective contraception during the study until 2 months after completion of the study vaccination series.  Exclusion Criteria:  Medical conditions  Any clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the study or might confound post-study intervention administration safety assessments (e.g., tattoos overlying either study intervention administration site). History of any reaction or hypersensitivity likely to be exacerbated by any component of the study interventions, including a known history of severe allergic reaction (e.g., anaphylaxis) to any component of any of the study vaccines. Any history of Guillain-Barré syndrome. Any history of myocarditis or pericarditis. Acute or chronic clinically significant pulmonary, cardiovascular, hepatic or renal functional abnormality, as determined by medical history or physical examination. Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination (no laboratory testing required). Hypersensitivity to latex. For HZ/su and mRNA-1273 booster cohort: history of Herpes Zoster.  Prior/concomitant therapy  Use of any investigational or non-registered product (drug, vaccine or medical device) other than the study intervention(s) during the period beginning 30 days before the first dose of study intervention(s) (Day -29 to Day 1), or their planned use during the study period. Planned administration/administration of a vaccine not foreseen by the study protocol in the period starting 30 days before first dose and ending 30 days after the last dose of study intervention administration. However, for HZ/su and mRNA-1273 booster cohort: licensed pneumococcal vaccines and non-replicating vaccines (i.e., inactivated and subunit vaccines, including inactivated and subunit influenza vaccines, with or without adjuvant for seasonal or pandemic flu) may be administered up until 8 days prior to dose 1 of HZ/su and/or dose 2 of HZ/su and/or at least 14 days after any dose of HZ/su. For Flu D-QIV and mRNA-1273 booster cohort: licensed pneumococcal vaccines and non-replicating vaccines (i.e., inactivated and subunit vaccines, other than influenza vaccines) may be administered up until 8 days prior to dose 1 of Flu D-QIV and/or at least 30 days after any dose of Flu D-QIV. For time interval between other routine vaccines with mRNA-1273 booster dose (administered in the study), local guidelines must be followed.  In case emergency mass vaccination for an unforeseen public health threat (e.g., a pandemic) is organized by public health authorities outside the routine immunization program, the time period described above can be reduced if necessary for that mass vaccination vaccine, provided this vaccine is licensed and used according to its Product Information.  Administration of long-acting immune-modifying drugs at any time during the study period (e.g., infliximab). Administration of immunoglobulins and/or any blood products or plasma derivatives during the period starting 3 months before the first dose of study intervention(s) up to 1 month post last dose or planned administration during the study period. Prior planned or chronic administration (defined as more than 14 days in total) of immunosuppressants or other immune-modifying drugs during the period starting 3 months prior to the first vaccine. For corticosteroids, this will mean more than 14 days in total of prednisone ≥20 mg/day or equivalent is not allowed. Inhaled, intra-articular and topical steroids are allowed. For HZ/su and mRNA-1273 booster cohort: Previous vaccination against Herpes Zoster with the exception of receipt of live attenuated HZ vaccine. For Flu D-QIV and mRNA-1273 booster cohort: Administration of a seasonal influenza vaccine during the 6 months preceding entry into the study. Prior administration of an investigational or licensed coronavirus (SARS-CoV, MERS-CoV, SARS-CoV-2) vaccine except for mRNA-1273 vaccine. Any contraindication to the study intervention(s).  Prior/concurrent clinical study experience  • Planning to or concurrently participating in another clinical study (including current / planned simultaneous participation in another interventional study to prevent or treat COVID-19), at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational vaccine / product (drug or medical device).  Other exclusions  Pregnant or lactating female. Female planning to become pregnant or planning to discontinue contraceptive precautions within 2 months following last study vaccination. Indications of drug abuse or excess alcohol use as deemed by investigator to potentially confound safety assessments or render participant unable or unlikely to adhere to protocol requirements.