A Trial Investigating the Safety and Effects of One or Two Additional Doses of Comirnaty or One Dose of BNT162b2s01 in BNT162-01 or BNT162-04 Trial Subjects

Inclusion Criteria: * Had given informed consent by signing the informed consent form (ICF) before initiation of any trial-specific procedures. * Were willing and able to comply with scheduled visits, treatment schedule, laboratory tests, lifestyle restrictions (including those requested by the German and federal Governments, e.g., to follow good practices to reduce chances of spreading COVID 19), and other requirements of the trial. * Have received BNT162 vaccine candidates in the BNT162-01 or BNT162-04 trials. * Remained overall healthy (i.e., has not medically deteriorated significantly since participation in the parent trial, is not anticipated to die in the next 26 weeks, and is able to provide blood as specified by the trial without anticipated, deleterious medical consequences) in the clinical judgment of the investigator based on medical history and physical examination. Screening clinical laboratory tests are to assess the participants' "new baseline" unless required for eligibility. Note: in particular, caution should be used with a subject who has a history of cardiovascular disease, e.g., myocarditis, pericarditis, myocardial infarction, congestive heart failure, cardiomyopathy, or clinically significant arrhythmia. * Agreed not to enroll in another trial of an IMP, starting after Visit 0 and continuously until Visit 5 (Day 50). * Less than 18 months have passed since their last IMP injection in their parent trial. * If they received 30 μg Comirnaty twice in the …