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 hospitalization for worsening disease during the 6 weeks before enrollment, can be included. or for the immunocompromised cohort (cohort 13); volunteers who have previously received solid organ transplant, or peripheral blood stem cell transplantation ≥6 months after transplantation, or individuals with human immunodeficiency virus (hiv) infection with a cd4+ t-cell count of ≥200 x 10\^6 /l at visit 0. individuals with lower t-cell counts will be excluded from the trial on the basis that this represents a significant medical complication. in the clinical judgment of the investigator, volunteers must be immunocompromised but otherwise healthy. after consultation with the medical monitor, this may include individuals receiving immunosuppressant therapy due to another confounding disease at least 2 weeks prior to enrollment and/or at least 6 weeks following immunization with bnt162b2, and/or individuals with immunosuppressive treatment of an autoimmune disease if the disease is stable. * women of childbearing potential (wocbp) must have a negative beta-human chorionic gonadotropin urine test at visit 0 and visit 1. women that are postmenopausal or permanently sterilized will be considered as not having reproductive potential. * wocbp must agree to practice a highly effective form of contraception during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. wocbp must agree to require their male partners to use condoms during sexual contact (unless male partners are sterilized or infertile). * wocbp must confirm that they practice at least one highly effective form of contraception for the 14 days prior to visit 0. * wocbp must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. * men who are sexually active with a wocbp and have not had a vasectomy must agree to practice a highly effective form of contraception with their female partner of childbearing potential during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. * men must be willing to refrain from sperm donation, starting after visit 0 and continuously until 60 days after receiving the last immunization. * they must have confirmation of their health insurance coverage prior to visit 0. * they must agree to not be vaccinated during the trial, starting after visit 0 and continuously until 28 days after receiving the last immunization.

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 hospitalization for worsening disease during the 6 weeks before enrollment, can be included. or for the immunocompromised cohort (cohort 13); volunteers who have previously received solid organ transplant, or peripheral blood stem cell transplantation ≥6 months after transplantation, or individuals with human immunodeficiency virus (hiv) infection with a cd4+ t-cell count of ≥200 x 10\^6 /l at visit 0. individuals with lower t-cell counts will be excluded from the trial on the basis that this represents a significant medical complication. in the clinical judgment of the investigator, volunteers must be immunocompromised but otherwise healthy. after consultation with the medical monitor, this may include individuals receiving immunosuppressant therapy due to another confounding disease at least 2 weeks prior to enrollment and/or at least 6 weeks following immunization with bnt162b2, and/or individuals with immunosuppressive treatment of an autoimmune disease if the disease is stable. * women of childbearing potential (wocbp) must have a negative beta-human chorionic gonadotropin urine test at visit 0 and visit 1. women that are postmenopausal or permanently sterilized will be considered as not having reproductive potential. * wocbp must agree to practice a highly effective form of contraception during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. wocbp must agree to require their male partners to use condoms during sexual contact (unless male partners are sterilized or infertile). * wocbp must confirm that they practice at least one highly effective form of contraception for the 14 days prior to visit 0. * wocbp must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. * men who are sexually active with a wocbp and have not had a vasectomy must agree to practice a highly effective form of contraception with their female partner of childbearing potential during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. * men must be willing to refrain from sperm donation, starting after visit 0 and continuously until 60 days after receiving the last immunization. * they must have confirmation of their health insurance coverage prior to visit 0. * they must agree to not be vaccinated during the trial, starting after visit 0 and continuously until 28 days after receiving the last immunization.

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 hospitalization for worsening disease during the 6 weeks before enrollment, can be included. or for the immunocompromised cohort (cohort 13); volunteers who have previously received solid organ transplant, or peripheral blood stem cell transplantation ≥6 months after transplantation, or individuals with human immunodeficiency virus (hiv) infection with a cd4+ t-cell count of ≥200 x 10^6 /l at visit 0. individuals with lower t-cell counts will be excluded from the trial on the basis that this represents a significant medical complication. in the clinical judgment of the investigator, volunteers must be immunocompromised but otherwise healthy. after consultation with the medical monitor, this may include individuals receiving immunosuppressant therapy due to another confounding disease at least 2 weeks prior to enrollment and/or at least 6 weeks following immunization with bnt162b2, and/or individuals with immunosuppressive treatment of an autoimmune disease if the disease is stable. - women of childbearing potential (wocbp) must have a negative beta-human chorionic gonadotropin urine test at visit 0 and visit 1. women that are postmenopausal or permanently sterilized will be considered as not having reproductive potential. - wocbp must agree to practice a highly effective form of contraception during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. wocbp must agree to require their male partners to use condoms during sexual contact (unless male partners are sterilized or infertile). - wocbp must confirm that they practice at least one highly effective form of contraception for the 14 days prior to visit 0. - wocbp must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men who are sexually active with a wocbp and have not had a vasectomy must agree to practice a highly effective form of contraception with their female partner of childbearing potential during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men must be willing to refrain from sperm donation, starting after visit 0 and continuously until 60 days after receiving the last immunization. - they must have confirmation of their health insurance coverage prior to visit 0. - they must agree to not be vaccinated during the trial, starting after visit 0 and continuously until 28 days after receiving the last immunization.

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 hospitalization for worsening disease during the 6 weeks before enrollment, can be included. or for the immunocompromised cohort (cohort 13); volunteers who have previously received solid organ transplant, or peripheral blood stem cell transplantation ≥6 months after transplantation, or individuals with human immunodeficiency virus (hiv) infection with a cd4+ t-cell count of ≥200 x 10^6 /l at visit 0. individuals with lower t-cell counts will be excluded from the trial on the basis that this represents a significant medical complication. in the clinical judgment of the investigator, volunteers must be immunocompromised but otherwise healthy. after consultation with the medical monitor, this may include individuals receiving immunosuppressant therapy due to another confounding disease at least 2 weeks prior to enrollment and/or at least 6 weeks following immunization with bnt162b2, and/or individuals with immunosuppressive treatment of an autoimmune disease if the disease is stable. - women of childbearing potential (wocbp) must have a negative beta-human chorionic gonadotropin urine test at visit 0 and visit 1. women that are postmenopausal or permanently sterilized will be considered as not having reproductive potential. - wocbp must agree to practice a highly effective form of contraception during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. wocbp must agree to require their male partners to use condoms during sexual contact (unless male partners are sterilized or infertile). - wocbp must confirm that they practice at least one highly effective form of contraception for the 14 days prior to visit 0. - wocbp must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men who are sexually active with a wocbp and have not had a vasectomy must agree to practice a highly effective form of contraception with their female partner of childbearing potential during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men must be willing to refrain from sperm donation, starting after visit 0 and continuously until 60 days after receiving the last immunization. - they must have confirmation of their health insurance coverage prior to visit 0. - they must agree to not be vaccinated during the trial, starting after visit 0 and continuously until 28 days after receiving the last immunization.

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 hospitalization for worsening disease during the 6 weeks before enrollment, can be included. or for the immunocompromised cohort (cohort 13); volunteers who have previously received solid organ transplant, or peripheral blood stem cell transplantation ≥6 months after transplantation, or individuals with human immunodeficiency virus (hiv) infection with a cd4+ t-cell count of ≥200 x 106 /l. individuals with lower t-cell counts will be excluded from the trial on the basis that this represents a significant medical complication. in the clinical judgment of the investigator, volunteers must be immunocompromised but otherwise healthy. after consultation with the medical monitor, this may include individuals receiving immunosuppressant therapy due to another confounding disease at least 2 weeks prior to enrollment and/or at least 6 weeks following immunization with bnt162b2, and/or individuals with immunosuppressive treatment of an autoimmune disease if the disease is stable. - women of childbearing potential (wocbp) must have a negative beta-human chorionic gonadotropin urine test at visit 0 and visit 1. women that are postmenopausal or permanently sterilized will be considered as not having reproductive potential. - wocbp must agree to practice a highly effective form of contraception during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. wocbp must agree to require their male partners to use condoms during sexual contact (unless male partners are sterilized or infertile). - wocbp must confirm that they practice at least one highly effective form of contraception for the 14 days prior to visit 0. - wocbp must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men who are sexually active with a wocbp and have not had a vasectomy must agree to practice a highly effective form of contraception with their female partner of childbearing potential during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men must be willing to refrain from sperm donation, starting after visit 0 and continuously until 60 days after receiving the last immunization. - they must have confirmation of their health insurance coverage prior to visit 0. - they must agree to not be vaccinated during the trial, starting after visit 0 and continuously until 28 days after receiving the last immunization.

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 hospitalization for worsening disease during the 6 weeks before enrollment, can be included. or for the immunocompromised cohort (cohort 13); volunteers who have previously received solid organ transplant, or peripheral blood stem cell transplantation ≥6 months after transplantation, or individuals with human immunodeficiency virus (hiv) infection with a cd4+ t-cell count of ≥200 x 106 /l. individuals with lower t-cell counts will be excluded from the trial on the basis that this represents a significant medical complication. in the clinical judgment of the investigator, volunteers must be immunocompromised but otherwise healthy. after consultation with the medical monitor, this may include individuals receiving immunosuppressant therapy due to another confounding disease at least 2 weeks prior to enrollment and/or at least 6 weeks following immunization with bnt162b2, and/or individuals with immunosuppressive treatment of an autoimmune disease if the disease is stable. - women of childbearing potential (wocbp) must have a negative beta-human chorionic gonadotropin urine test at visit 0 and visit 1. women that are postmenopausal or permanently sterilized will be considered as not having reproductive potential. - wocbp must agree to practice a highly effective form of contraception during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. wocbp must agree to require their male partners to use condoms during sexual contact (unless male partners are sterilized or infertile). - wocbp must confirm that they practice at least one highly effective form of contraception for the 14 days prior to visit 0. - wocbp must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men who are sexually active with a wocbp and have not had a vasectomy must agree to practice a highly effective form of contraception with their female partner of childbearing potential during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men must be willing to refrain from sperm donation, starting after visit 0 and continuously until 60 days after receiving the last immunization. - they must have confirmation of their health insurance coverage prior to visit 0. - they must agree to not be vaccinated during the trial, starting after visit 0 and continuously until 28 days after receiving the last immunization.

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 subject cohorts, volunteers must be aged 18 to 55 years, have a body mass index 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 body mass index 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. - women of childbearing potential (wocbp) must have a negative beta-human chorionic gonadotropin urine test at visit 0 and visit 1. women that are postmenopausal or permanently sterilized will be considered as not having reproductive potential. - wocbp must agree to practice a highly effective form of contraception during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. wocbp must agree to require their male partners to use condoms during sexual contact (unless male partners are sterilized or infertile). - wocbp must confirm that they practice at least one highly effective form of contraception for the 14 days prior to visit 0. - wocbp must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men who are sexually active with a wocbp and have not had a vasectomy must agree to practice a highly effective form of contraception with their female partner of childbearing potential during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men must be willing to refrain from sperm donation, starting after visit 0 and continuously until 60 days after receiving the last immunization. - they must have confirmation of their health insurance coverage prior to visit 0. - they must agree to not be vaccinated during the trial, starting after visit 0 and continuously until 28 days after receiving the last immunization.

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 subject cohorts, volunteers must be aged 18 to 55 years, have a body mass index 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 body mass index 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. - women of childbearing potential (wocbp) must have a negative beta-human chorionic gonadotropin urine test at visit 0 and visit 1. women that are postmenopausal or permanently sterilized will be considered as not having reproductive potential. - wocbp must agree to practice a highly effective form of contraception during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. wocbp must agree to require their male partners to use condoms during sexual contact (unless male partners are sterilized or infertile). - wocbp must confirm that they practice at least one highly effective form of contraception for the 14 days prior to visit 0. - wocbp must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men who are sexually active with a wocbp and have not had a vasectomy must agree to practice a highly effective form of contraception with their female partner of childbearing potential during the trial, starting after visit 0 and continuously until 60 days after receiving the last immunization. - men must be willing to refrain from sperm donation, starting after visit 0 and continuously until 60 days after receiving the last immunization. - they must have confirmation of their health insurance coverage prior to visit 0. - they must agree to not be vaccinated during the trial, starting after visit 0 and continuously until 28 days after receiving the last immunization.