inclusion criteria: 1. healthy adults ≥ 18 years of age at time of enrollment. 2. vaccinated with an eua or approved vaccine against covid-19 ≥ 3 months prior to enrollment on study or infection with covid-19 ≥ 3 months prior to enrollment on study. 3. able to understand and provide a signed informed consent that fulfills the relevant institutional review board (irb) or independent ethics committee (iec) guidelines. 4. agrees to the collection of biospecimens (eg, nasopharyngeal \[np\] swabs) and venous blood per protocol. 5. ability to attend required study visits and return for adequate follow-up, as required by this protocol. 6. temperature \< 38°c. 7. agreement to practice effective contraception for female participants of childbearing potential and non-sterile males. female participants of childbearing potential must agree to use effective contraception while on study until at least 1 month after the last dose of vaccine. non-sterile male participants must agree to use a condom while on study until at least 1 month after the last dose of vaccine. effective contraception includes surgical sterilization (eg, vasectomy, tubal ligation), two forms of barrier methods (eg, condom, diaphragm), intrauterine devices (iuds), oral contraceptives, injectable contraceptives, patches, implants and abstinence. 8. hiv-positive participants must have been on anti-retroviral therapy for ≥ 4 weeks and have hiv-1 viral load \< 1,000 copies/ml at the time of enrollment.

inclusion criteria: 1. healthy adults ≥ 18 years of age at time of enrollment. 2. vaccinated with an eua or approved vaccine against covid-19 ≥ 3 months prior to enrollment on study or infection with covid-19 ≥ 3 months prior to enrollment on study. 3. able to understand and provide a signed informed consent that fulfills the relevant institutional review board (irb) or independent ethics committee (iec) guidelines. 4. agrees to the collection of biospecimens (eg, nasopharyngeal \[np\] swabs) and venous blood per protocol. 5. ability to attend required study visits and return for adequate follow-up, as required by this protocol. 6. temperature \< 38°c. 7. agreement to practice effective contraception for female participants of childbearing potential and non-sterile males. female participants of childbearing potential must agree to use effective contraception while on study until at least 1 month after the last dose of vaccine. non-sterile male participants must agree to use a condom while on study until at least 1 month after the last dose of vaccine. effective contraception includes surgical sterilization (eg, vasectomy, tubal ligation), two forms of barrier methods (eg, condom, diaphragm), intrauterine devices (iuds), oral contraceptives, injectable contraceptives, patches, implants and abstinence. 8. hiv-positive participants must have been on anti-retroviral therapy for ≥ 4 weeks and have hiv-1 viral load \< 1,000 copies/ml at the time of enrollment.

inclusion criteria: healthy adults ≥ 18 years of age at time of enrollment. vaccinated with an eua or approved vaccine against covid-19 ≥ 3 months prior to enrollment on study or infection with covid-19 ≥ 3 months prior to enrollment on study. able to understand and provide a signed informed consent that fulfills the relevant institutional review board (irb) or independent ethics committee (iec) guidelines. agrees to the collection of biospecimens (eg, nasopharyngeal [np] swabs) and venous blood per protocol. ability to attend required study visits and return for adequate follow-up, as required by this protocol. temperature < 38°c. agreement to practice effective contraception for female participants of childbearing potential and non-sterile males. female participants of childbearing potential must agree to use effective contraception while on study until at least 1 month after the last dose of vaccine. non-sterile male participants must agree to use a condom while on study until at least 1 month after the last dose of vaccine. effective contraception includes surgical sterilization (eg, vasectomy, tubal ligation), two forms of barrier methods (eg, condom, diaphragm), intrauterine devices (iuds), oral contraceptives, injectable contraceptives, patches, implants and abstinence. hiv-positive participants must have been on anti-retroviral therapy for ≥ 4 weeks and have hiv-1 viral load < 1,000 copies/ml at the time of enrollment.

inclusion criteria: healthy adults ≥ 18 years of age at time of enrollment. vaccinated with an eua or approved vaccine against covid-19 ≥ 3 months prior to enrollment on study or infection with covid-19 ≥ 3 months prior to enrollment on study. able to understand and provide a signed informed consent that fulfills the relevant institutional review board (irb) or independent ethics committee (iec) guidelines. agrees to the collection of biospecimens (eg, nasopharyngeal [np] swabs) and venous blood per protocol. ability to attend required study visits and return for adequate follow-up, as required by this protocol. temperature < 38°c. agreement to practice effective contraception for female participants of childbearing potential and non-sterile males. female participants of childbearing potential must agree to use effective contraception while on study until at least 1 month after the last dose of vaccine. non-sterile male participants must agree to use a condom while on study until at least 1 month after the last dose of vaccine. effective contraception includes surgical sterilization (eg, vasectomy, tubal ligation), two forms of barrier methods (eg, condom, diaphragm), intrauterine devices (iuds), oral contraceptives, injectable contraceptives, patches, implants and abstinence. hiv-positive participants must have been on anti-retroviral therapy for ≥ 4 weeks and have hiv-1 viral load < 1,000 copies/ml at the time of enrollment.