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.  Exclusion Criteria:  Known history of SARS-CoV-2 or SARS-CoV-1 infection; Previously received an investigational coronavirus vaccine; Previously received a SARS-CoV-2 monoclonal antibody; Current or planned simultaneous participation in another interventional study; A history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a COVID-19 vaccine, or otherwise have a contraindication to one of the available study vaccines per the approved label; Individuals who are immunocompromised (e.g. active leukaemia or lymphoma, generalised malignancy, aplastic anaemia, solid organ transplant, bone marrow transplant, current radiation therapy congenital immunodeficiency, HIV/AIDS with CD4 lymphocyte count < 200 and patients on immunosuppressant medications); Received systemic immunosuppressants or immune-modifying drugs for >14 days in total within 6 months prior to Screening (for corticosteroids >/= 20 milligram per day of prednisone equivalent). Topical tacrolimus is allowed if not used within 14 days prior to Day 1; Individuals who are pregnant or breast feeding; Chronic illness that, in the opinion of the study team, is at a stage where it might interfere with trial conduct or completion; Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalised involuntarily; Current alcohol abuse or drug addiction that might interfere with the ability to comply with trial procedures in the opinion of the study team; Moderate or severe acute illness/infection (according to study team's judgement) on the day of vaccination, or febrile illness (temperature ≥ 37.5°C). A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided.