The purpose of this clinical trial is to learn about the safety and effects of the study medicine (called PF-07275315) in healthy participants.

This study is seeking participants who:

• Are healthy as determined by medical evaluation.
• Are willing and able to comply with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations, and other study procedures.
• Have a body mass index (BMI) of 17.5 to 32 kilogram per meter square - a total body weight of more than 50 kilograms (110 pounds)

Participants will be divided randomly into 8 different groups. All participants will receive either one PF-07275315 or a harmless treatment that has no medical effect (placebo) intravenous (IV) infusion (given directly into a vein). Participants will take part in this study for up to 541 days. During this time, eligible participants will receive single increasing amounts of PF-07275315 or placebo. Increase will only occur if the sponsor agrees that the next dose is likely to have acceptable safety and tolerability. The follow-up visit will take place 271 days after first treatment.

This is an first-in-human within-cohort randomized, participant- and investigator-blind, sponsor-open, placebo-controlled study of the safety, tolerability, PK, and PD following single and multiple escalating doses of PF-07275315 that will be conducted in healthy adults.

This study is seeking participants who:

• Are overtly healthy as determined by medical evaluation.
• Are willing and able to comply with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations, and other study procedures.
• Have a body mass index (BMI) of 17.5 to 32 kg/m2; and a total body weight >50 kg (110 lb).

This study is not seeking participants who have:

• Evidence of active, latent, or inadequately treated infection with Mycobacterium tuberculosis (TB) as defined by both of the following
• History of human immunodeficiency virus (HIV) infection, hepatitis B, or hepatitis C;
• Any of the following acute or chronic infections or infection history
• Any malignancies or have a history of malignancies with the exception of adequately treated or excised non-metastatic basal cell or squamous cell cancer of the skin, or cervical carcinoma in situ.
• Have undergone significant trauma or major surgery within 1 month of the first dose of study drug.

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.