inclusion criteria: willing and able to provide informed consent for participation in this study; aged ≥21years at the time of study enrolment; received the second dose of bnt162b2 or mrna-1273 coronavirus disease 2019 vaccines at least 6 months prior to enrolment; willing and able to comply with all scheduled visits, vaccination plan, laboratory tests and other study procedures.

inclusion criteria: willing and able to provide informed consent for participation in this study; aged ≥21years at the time of study enrolment; received the second dose of bnt162b2 or mrna-1273 coronavirus disease 2019 vaccines at least 6 months prior to enrolment; willing and able to comply with all scheduled visits, vaccination plan, laboratory tests and other study procedures.