The purpose of this clinical trial is to learn about a pneumococcal vaccine with a new ingredient (PF-07872411) intended to enhance the effects of the vaccine. This pneumococcal vaccine with the new ingredient may prevent the diseases caused by pneumococcal bacteria like meningitis, sepsis, ear infections and sinusitis.

Meningitis is an infection in which the tissue around the brain and spine is swollen.

Sepsis is a very serious infection in your blood caused by a germ (a bacteria). Sinusitis is when your sinuses (the air-filled spaces inside your nose and head), are infected.

This study is seeking for healthy participants who:

• are above 50 years of age and less than 64 years of age.
• have not taken any vaccine for pneumococcal diseases before.
• have not taken any vaccines with additional ingredients within 1 year before administration of the study vaccine.

All participants will receive a single study vaccine shot in the upper arm muscle at the study clinic. The study will compare the experiences of people receiving the vaccine with a new ingredient in the vaccine to those without the new ingredient. This will be done by comparing 2 different dose levels of the new ingredient. It will also be compared against people who receive the vaccine without the new ingredient and at different dose levels. This will help the study team establish if the vaccine with a new ingredient is safe and effective.

Participants will take part in this study for about 12 months. During this time participants will have up to 6 clinic visits. At these clinic visits, participants will be asked if any side effects were experienced. The participants will also have to give blood samples during these visits.

Some participants will need to have blood taken for laboratory tests before they can be judged to be eligible to be included in the study.

Inclusion Criteria:

• Male or female participants ≥50 and ≤64 years of age at the time of consent.
• Adults determined by clinical assessment, including medical history and clinical judgment, to be eligible for the study, including those with preexisting stable disease, defined as disease not requiring significant change in therapy or hospitalization for worsening disease, within 6 months before receipt of study intervention.
• Female participants of childbearing potential or male participants able to father children and who are willing to use acceptable methods of contraception for at least 28 days after the last dose of study intervention; or female participants not of childbearing potential; or male participants not able to father children.

Exclusion Criteria:

• History of a severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component in pneumococcal conjugate vaccines and any other diphtheria toxoid-containing vaccine.
• Serious chronic disorder, including history of metastatic malignancy, severe COPD requiring supplemental oxygen, end-stage renal disease with or without dialysis, cirrhosis of the liver, clinically unstable cardiac disease, or any other disorder, that in the investigator's opinion, would make the participant inappropriate for entry into the study.
• History of microbiologically proven invasive disease caused by S pneumoniae.
• Current febrile illness (body temperature ≥100.4°F [≥38.0°C]) or other acute illness within 48 hours before study intervention administration.
• Pregnant female participants or breastfeeding female participants (known or suspected).
• Previous vaccination with any licensed or investigational pneumococcal vaccine, or planned receipt of any licensed or investigational pneumococcal vaccine through study participation.
• Receipt of any inactivated or otherwise nonlive vaccine within 14 days or any live vaccine within 28 days before administration of study intervention.
• Receipt of an adjuvanted vaccine containing QS-21 (or similar saponin adjuvant), MPL, or MF59 within 1 year before administration of study intervention

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.