The purpose of this clinical study is to learn about the safety and effects of the study medicine (called PF-07999415) in healthy adult participants. This study is seeking volunteers aged 18 to 65 years old who do not have any major health issues. Some participants in this study will receive a single dose of PF-07999415 as a shot in the thigh, abdomen, or arm at the study clinic. Afterward, participants will stay in a hospital-like setting for 2 weeks, where they will be monitored for reactions to the study medicine. The study team will compare the experiences of people receiving PF-07999415 to those of the people who do not. This will help the study team decide if PF-07999415 is safe. Participants will take part in this study for 3 to 7 months. During this time, participants will stay at the healthcare facility for 2 weeks and then come back for study visits every 2 weeks until completing the study.