Inclusion Criteria:  Adult subjects (18 years old) having received a prime VAXZEVRIA vaccination between 8 and 12 weeks before the screening visit Participants must provide consent indicating that he or she understands the purpose, procedures and potential risks and benefits of the study, and is willing to participate in the study. Subjects in good health or stable clinical situation. Participant is willing and able to adhere to the procedures specified in this protocol  Exclusion Criteria:  Participant has a clinically significant acute illness (this does not include minor illnesses such as diarrhea or mild upper respiratory tract infection) or temperature ≥38.0ºC within 24 hours prior to the planned dose of study vaccine. Participant has a known or suspected allergy or history of anaphylaxis or other serious adverse reactions to COMIRNATY excipients. Subjects with any contraindication to the administration of COMIRNATY, included pregnancy. Subjects with prior documented COVID19 since VAXZEVRIA vaccination. Subjects have symptoms or signs compatible with COVID19. Subjects participating in a clinical trial in the last three months. Any condition or situation precluding or interfering the compliance with the protocol.