A Trial Investigating the Safety and Effects of Four BNT162 Vaccines Against COVID-19 in Healthy and Immunocompromised Adults

Inclusion Criteria: * Have given informed consent by signing the informed consent form (ICF) before initiation of any trial-specific procedures. * They must be willing and able to comply with scheduled visits, treatment schedule, laboratory tests, lifestyle restrictions (e.g., to practice social distancing and to follow good practices to reduce their chances of being infected or spreading COVID-19), and other requirements of the trial. * They must be able to understand and follow trial-related instructions. * For younger adult cohorts, volunteers must be aged 18 to 55 years, have a body mass index (BMI) over 19 kg/m\^2 and under 30 kg/m\^2, and weigh at least 50 kg at Visit 0. OR For older adult cohorts, volunteers must be aged 56 to 85 years, have a BMI over 19 kg/m\^2 and under 30 kg/m\^2, and weigh at least 50 kg at Visit 0. OR For the immunocompromised adult cohort (Cohort 13), volunteers must be aged 18 to 85 years, have a BMI over 19 kg/m\^2 and under 30 kg/m\^2, and weigh at least 50 kg at Visit 0. * They must be healthy, in the clinical judgment of the investigator, based on medical history, physical examination, 12-lead electrocardiogram (ECG), vital signs (systolic/diastolic blood pressure, pulse rate, body temperature, respiratory rate), and clinical laboratory tests (blood chemistry, hematology, and urine chemistry) at Visit 0. Note: Healthy volunteers with pre-existing stable disease, defined as disease not requiring significant change in therapy or hospitalizat…