substudy a inclusion criteria: * male or female participants ≥16 years of age at visit 1 (day 1) who participated in c4591001. * participants who are willing and able to comply with all scheduled visits, vaccination plan, laboratory tests, lifestyle considerations, and other study procedures. * healthy participants who are determined by medical history, physical examination (if required), and clinical judgment of the investigator to be eligible for inclusion in the study. * capable of giving signed informed consent. * participants who have received 2 prior doses of 30 µg bnt162b2 19-42 days apart, with the second dose being at least 175 days before visit 1 (day 1).

substudy a inclusion criteria: * male or female participants ≥16 years of age at visit 1 (day 1) who participated in c4591001. * participants who are willing and able to comply with all scheduled visits, vaccination plan, laboratory tests, lifestyle considerations, and other study procedures. * healthy participants who are determined by medical history, physical examination (if required), and clinical judgment of the investigator to be eligible for inclusion in the study. * capable of giving signed informed consent. * participants who have received 2 prior doses of 30 µg bnt162b2 19-42 days apart, with the second dose being at least 175 days before visit 1 (day 1).

substudy a inclusion criteria: male or female participants ≥16 years of age at visit 1 (day 1) who participated in c4591001. participants who are willing and able to comply with all scheduled visits, vaccination plan, laboratory tests, lifestyle considerations, and other study procedures. healthy participants who are determined by medical history, physical examination (if required), and clinical judgment of the investigator to be eligible for inclusion in the study. capable of giving signed informed consent. participants who have received 2 prior doses of 30 µg bnt162b2 19-42 days apart, with the second dose being at least 175 days before visit 1 (day 1).

substudy a inclusion criteria: male or female participants ≥16 years of age at visit 1 (day 1) who participated in c4591001. participants who are willing and able to comply with all scheduled visits, vaccination plan, laboratory tests, lifestyle considerations, and other study procedures. healthy participants who are determined by medical history, physical examination (if required), and clinical judgment of the investigator to be eligible for inclusion in the study. capable of giving signed informed consent. participants who have received 2 prior doses of 30 µg bnt162b2 19-42 days apart, with the second dose being at least 175 days before visit 1 (day 1).

inclusion criteria: - male or female participants ≥16 years of age at visit 1 (day 1) who participated in c4591001. - participants who are willing and able to comply with all scheduled visits, vaccination plan, laboratory tests, lifestyle considerations, and other study procedures. - healthy participants who are determined by medical history, physical examination (if required), and clinical judgment of the investigator to be eligible for inclusion in the study. - capable of giving signed informed consent. - participants who have received 2 prior doses of 30 µg bnt162b2 19-42 days apart, with the second dose being at least 175 days before visit 1 (day 1).

inclusion criteria: - male or female participants ≥16 years of age at visit 1 (day 1) who participated in c4591001. - participants who are willing and able to comply with all scheduled visits, vaccination plan, laboratory tests, lifestyle considerations, and other study procedures. - healthy participants who are determined by medical history, physical examination (if required), and clinical judgment of the investigator to be eligible for inclusion in the study. - capable of giving signed informed consent. - participants who have received 2 prior doses of 30 µg bnt162b2 19-42 days apart, with the second dose being at least 175 days before visit 1 (day 1).