Intradermal Administration of a COVID-19 mRNA Vaccine in Elderly

Inclusion Criteria: * Male or female aged ≥75 years at the moment of immunization. * Healthy, determined by medical history and clinical judgement of the investigator. Participants with a pre-existing illness that is stable, defined as disease not requiring significant change in therapy or hospitalisation during the 6 weeks before enrolment and not expected to require any intervention during the study, can be included. * Willing and able to comply with all scheduled visits, vaccination plan, laboratory tests, and other study procedures. * Willing to postpone their regular COVID-19 vaccination upon invitation by the Municipal Health Service or general practitioner until at least four months after receiving the intervention. * Completed a primary series of COVID-19 vaccination. * Capable and willing to give personal signed informed consent. * Adequate understanding of the procedures of the study and agrees to abide strictly thereby. * Fully conversant in the Dutch language. * Agrees his/her general practitioner is informed about participation in the study. * Agrees to provide access to information regarding their vaccination background. * Agrees that the study physician and his/her delegates have access to their medical file at Radboudumc. Exclusion Criteria: * Medical or psychiatric condition that may increase the risk of study participation or, in the investigator's judgement, make the participant inappropriate for the study. * No decision-making capacity. * History of severe adverse reaction to a vaccine or to any component of the study intervention. * Thrombose with thrombocytopenia syndrome after vaccination with a COVID-19 vaccine. * Dermatological conditions that might interfere with the ID vaccination. * Receipt of COVID-19 vaccination within 3 months before receiving the study intervention. * Known or suspected immunodeficiency, as determined by medical history or medication use (inhalation corticosteroids are allowed). * History of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. * Bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate IM injection. * Participation in other studies involving other study interventions within 28 days prior and during 28 days after receiving the study intervention. * Receipt of any other non-study vaccine within 28 days prior and after receiving the study intervention.