individuals who meet any of these criteria are not eligible for enrollment as study participants- 1. currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine 2. recipient of any allograft other than a kidney or liver 3. participant is pregnant 4. any past history of donor specific antibody (dsa) using local site standards 5. prior receipt of the moderna covid-19 vaccine 2023-2024 or pfizer-biontech covid-19 vaccine 2023-2024. 6. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression 7. known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine 8. thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine 9. history of heparin-induced thrombocytopenia 10. any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months 11. more than minimal graft dysfunction, in accordance with study definition 12. receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment 13. concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction 14. any untreated active infection including bk viremia \>10\^4 copies 15. infection with human immunodeficiency virus (hiv) 16. recent (within one year) or ongoing treatment for malignancy with the exception of: * non- melanomatous skin cancer definitively treated by local therapy, and * definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) 17. treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or 18. any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: * pose additional risks from participation in the study, * interfere with the candidate's ability to comply with study requirements, or * impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- 1. currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine 2. recipient of any allograft other than a kidney or liver 3. participant is pregnant 4. any past history of donor specific antibody (dsa) using local site standards 5. prior receipt of the moderna covid-19 vaccine 2023-2024 or pfizer-biontech covid-19 vaccine 2023-2024. 6. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression 7. known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine 8. thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine 9. history of heparin-induced thrombocytopenia 10. any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months 11. more than minimal graft dysfunction, in accordance with study definition 12. receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment 13. concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction 14. any untreated active infection including bk viremia \>10\^4 copies 15. infection with human immunodeficiency virus (hiv) 16. recent (within one year) or ongoing treatment for malignancy with the exception of: * non- melanomatous skin cancer definitively treated by local therapy, and * definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) 17. treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or 18. any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: * pose additional risks from participation in the study, * interfere with the candidate's ability to comply with study requirements, or * impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine recipient of any allograft other than a kidney or liver participant is pregnant any past history of donor specific antibody (dsa) using local site standards prior receipt of the moderna covid-19 vaccine 2023-2024 or pfizer-biontech covid-19 vaccine 2023-2024. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine history of heparin-induced thrombocytopenia any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months more than minimal graft dysfunction, in accordance with study definition receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction any untreated active infection including bk viremia >10^4 copies infection with human immunodeficiency virus (hiv) recent (within one year) or ongoing treatment for malignancy with the exception of: non- melanomatous skin cancer definitively treated by local therapy, and definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: pose additional risks from participation in the study, interfere with the candidate's ability to comply with study requirements, or impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine recipient of any allograft other than a kidney or liver participant is pregnant any past history of donor specific antibody (dsa) using local site standards prior receipt of the moderna covid-19 vaccine 2023-2024 or pfizer-biontech covid-19 vaccine 2023-2024. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine history of heparin-induced thrombocytopenia any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months more than minimal graft dysfunction, in accordance with study definition receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction any untreated active infection including bk viremia >10^4 copies infection with human immunodeficiency virus (hiv) recent (within one year) or ongoing treatment for malignancy with the exception of: non- melanomatous skin cancer definitively treated by local therapy, and definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: pose additional risks from participation in the study, interfere with the candidate's ability to comply with study requirements, or impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine recipient of any allograft other than a kidney or liver participant is pregnant any past history of donor specific antibody (dsa) using local site standards prior receipt of the moderna bivalent covid-19 vaccine or pfizer-biontech bivalent covid-19 vaccine. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine history of heparin-induced thrombocytopenia any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months more than minimal graft dysfunction, in accordance with study definition receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction any untreated active infection including bk viremia >10^4 copies infection with human immunodeficiency virus (hiv) recent (within one year) or ongoing treatment for malignancy with the exception of: non- melanomatous skin cancer definitively treated by local therapy, and definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: pose additional risks from participation in the study, interfere with the candidate's ability to comply with study requirements, or impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine recipient of any allograft other than a kidney or liver participant is pregnant any past history of donor specific antibody (dsa) using local site standards prior receipt of the moderna bivalent covid-19 vaccine or pfizer-biontech bivalent covid-19 vaccine. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine history of heparin-induced thrombocytopenia any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months more than minimal graft dysfunction, in accordance with study definition receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction any untreated active infection including bk viremia >10^4 copies infection with human immunodeficiency virus (hiv) recent (within one year) or ongoing treatment for malignancy with the exception of: non- melanomatous skin cancer definitively treated by local therapy, and definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: pose additional risks from participation in the study, interfere with the candidate's ability to comply with study requirements, or impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine recipient of any allograft other than a kidney or liver participant is pregnant any past history of donor specific antibody (dsa) using local site standards currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression recipients of any covid-19 vaccine other than the moderna covid-19 vaccine or the pfizer-biontech covid-19 vaccine known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine history of heparin-induced thrombocytopenia any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months more than minimal graft dysfunction, in accordance with study definition receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction any untreated active infection including bk viremia >10^4 copies infection with human immunodeficiency virus (hiv) recent (within one year) or ongoing treatment for malignancy with the exception of: non- melanomatous skin cancer definitively treated by local therapy, and definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: pose additional risks from participation in the study, interfere with the candidate's ability to comply with study requirements, or impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine recipient of any allograft other than a kidney or liver participant is pregnant any past history of donor specific antibody (dsa) using local site standards currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression recipients of any covid-19 vaccine other than the moderna covid-19 vaccine or the pfizer-biontech covid-19 vaccine known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine history of heparin-induced thrombocytopenia any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months more than minimal graft dysfunction, in accordance with study definition receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction any untreated active infection including bk viremia >10^4 copies infection with human immunodeficiency virus (hiv) recent (within one year) or ongoing treatment for malignancy with the exception of: non- melanomatous skin cancer definitively treated by local therapy, and definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: pose additional risks from participation in the study, interfere with the candidate's ability to comply with study requirements, or impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- 1. currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine 2. recipient of any allograft other than a kidney or liver 3. participant is pregnant 4. any past history of donor specific antibody (dsa) using local site standards 5. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression 6. recipients of any covid-19 vaccine other than the moderna covid-19 vaccine or the pfizer-biontech covid-19 vaccine 7. known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine 8. thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine 9. history of heparin-induced thrombocytopenia 10. any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months 11. more than minimal graft dysfunction, in accordance with study definition 12. receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment 13. concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction 14. any untreated active infection including bk viremia >10^4 copies 15. infection with human immunodeficiency virus (hiv) 16. recent (within one year) or ongoing treatment for malignancy with the exception of: - non- melanomatous skin cancer definitively treated by local therapy, and - definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) 17. treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or 18. any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: - pose additional risks from participation in the study, - interfere with the candidate's ability to comply with study requirements, or - impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- 1. currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine 2. recipient of any allograft other than a kidney or liver 3. participant is pregnant 4. any past history of donor specific antibody (dsa) using local site standards 5. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression 6. recipients of any covid-19 vaccine other than the moderna covid-19 vaccine or the pfizer-biontech covid-19 vaccine 7. known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine 8. thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine 9. history of heparin-induced thrombocytopenia 10. any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months 11. more than minimal graft dysfunction, in accordance with study definition 12. receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment 13. concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction 14. any untreated active infection including bk viremia >10^4 copies 15. infection with human immunodeficiency virus (hiv) 16. recent (within one year) or ongoing treatment for malignancy with the exception of: - non- melanomatous skin cancer definitively treated by local therapy, and - definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) 17. treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or 18. any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: - pose additional risks from participation in the study, - interfere with the candidate's ability to comply with study requirements, or - impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- 1. currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine 2. recipient of any allograft other than a kidney or liver 3. participant is pregnant 4. any past history of donor specific antibody (dsa) using local site standards 5. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression 6. recipients of any covid-19 vaccine other than the moderna covid-19 vaccine or the pfizer bion-tech covid-19 vaccine 7. known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine 8. thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine 9. history of heparin-induced thrombocytopenia 10. any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months 11. more than minimal graft dysfunction, in accordance with study definition 12. receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment 13. concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction 14. any untreated active infection including bk viremia >10^4 copies 15. infection with human immunodeficiency virus (hiv) 16. recent (within one year) or ongoing treatment for malignancy with the exception of: - non- melanomatous skin cancer definitively treated by local therapy, and - definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) 17. treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or 18. any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: - pose additional risks from participation in the study, - interfere with the candidate's ability to comply with study requirements, or - impact the quality or interpretation of the data obtained from the study.

individuals who meet any of these criteria are not eligible for enrollment as study participants- 1. currently on an immunosuppressive regimen different from the three regimens described in the inclusion criteria, for example (but not limited to) those including sirolimus, everolimus, belatacept, or azathioprine 2. recipient of any allograft other than a kidney or liver 3. participant is pregnant 4. any past history of donor specific antibody (dsa) using local site standards 5. currently taking any systemic immunosuppressive agent, other than their prescribed transplant immunosuppression 6. recipients of any covid-19 vaccine other than the moderna covid-19 vaccine or the pfizer bion-tech covid-19 vaccine 7. known history of severe allergic reaction to any component of an authorized or licensed covid-19 vaccine 8. thrombotic events, myocarditis, or pericarditis temporally associated with a prior dose of covid-19 vaccine 9. history of heparin-induced thrombocytopenia 10. any change in transplant immunosuppression regimen (drug or dose) in response to suspected or proven rejection within the last 6 months 11. more than minimal graft dysfunction, in accordance with study definition 12. receipt of any cellular depleting agent (e.g. antithymocyte globulins (atg), rituximab, alemtuzumab, cyclophosphamide) within 12 months preceding enrollment 13. concurrent autoimmune disease at risk for exacerbation with immunosuppression reduction 14. any untreated active infection including bk viremia >10^4 copies 15. infection with human immunodeficiency virus (hiv) 16. recent (within one year) or ongoing treatment for malignancy with the exception of: - non- melanomatous skin cancer definitively treated by local therapy, and - definitively treated carcinoma-in-situ of the cervix (stage 0 cervical cancer) 17. treatment or prophylaxis of covid-19 with a monoclonal antibody product or convalescent plasma within 6 months preceding enrollment, or 18. any past or current medical problems, treatments, or findings which, in the opinion of the investigator, may: - pose additional risks from participation in the study, - interfere with the candidate's ability to comply with study requirements, or - impact the quality or interpretation of the data obtained from the study.