known pregnant and/or lactating women. subject with a significant medical, neuro-psychiatric, or surgical condition, currently uncontrolled by treatment, which, in the principal investigator's opinion, may interfere with completion of the study. subjects with active diagnosis of acute leukaemia. subjects treated with bone marrow transplant < 90 days before received vaccination against sars-cov-2. subjects with a known history of hiv infection. covid-19 infection in the last 28 days prior to subject enrolment. subjects receiving prolonged and/or high doses of systemic immunosuppressive therapies including corticosteroids during the last 28 days before receiving first dose of vaccination against sars-cov-2 and up to subject enrolment. subjects who, for any reason, did not receive the 2nd dose of the anti-sars-cov-2 mrna vaccine. subjects that received the 3rd dose of anti-sars-cov-2 mrna vaccine prior to study entry. exclusion criterion number 9 is only applicable for previous versions of the protocol and is not applicable from protocol version 3.0 and subsequent versions. subject that received any dose of non-mrna anti-sars-cov-2 vaccine platform. subject with a known or suspected history of severe adverse reactions associated with a vaccine and/or with severe allergic reaction to vaccine components or anaphylaxis in the past. subjects who planned to receive any other licensed vaccines for other indications within 28 days prior to the first booster dose after icf signature or who are planning to receive any other vaccine up to 14 days after the first booster dose of the mrna anti-sars-cov-2 vaccine after icf signature (28 days for live attenuated vaccines). for influenza vaccination, a shorter interval or simultaneous administration is acceptable. subjects who have planned to receive a booster dose after icf signature but before the baseline assessment

known pregnant and/or lactating women. subject with a significant medical, neuro-psychiatric, or surgical condition, currently uncontrolled by treatment, which, in the principal investigator's opinion, may interfere with completion of the study. subjects with active diagnosis of acute leukaemia. subjects treated with bone marrow transplant < 90 days before received vaccination against sars-cov-2. subjects with a known history of hiv infection. covid-19 infection in the last 28 days prior to subject enrolment. subjects receiving prolonged and/or high doses of systemic immunosuppressive therapies including corticosteroids during the last 28 days before receiving first dose of vaccination against sars-cov-2 and up to subject enrolment. subjects who, for any reason, did not receive the 2nd dose of the anti-sars-cov-2 mrna vaccine. subjects that received the 3rd dose of anti-sars-cov-2 mrna vaccine prior to study entry. exclusion criterion number 9 is only applicable for previous versions of the protocol and is not applicable from protocol version 3.0 and subsequent versions. subject that received any dose of non-mrna anti-sars-cov-2 vaccine platform. subject with a known or suspected history of severe adverse reactions associated with a vaccine and/or with severe allergic reaction to vaccine components or anaphylaxis in the past. subjects who planned to receive any other licensed vaccines for other indications within 28 days prior to the first booster dose after icf signature or who are planning to receive any other vaccine up to 14 days after the first booster dose of the mrna anti-sars-cov-2 vaccine after icf signature (28 days for live attenuated vaccines). for influenza vaccination, a shorter interval or simultaneous administration is acceptable. subjects who have planned to receive a booster dose after icf signature but before the baseline assessment

- known pregnant and/or lactating women. - subject with a significant medical, neuro-psychiatric, or surgical condition, currently uncontrolled by treatment, which, in the principal investigator's opinion, may interfere with completion of the study. - subjects with active diagnosis of acute leukaemia. - subjects treated with bone marrow transplant < 90 days before received vaccination against sars-cov-2. - subjects with a known history of hiv infection. - covid-19 infection in the last 28 days before receiving first dose of vaccination against sars-cov-2 and up to subject enrolment. - subjects receiving prolonged and/or high doses of systemic immunosuppressive therapies including corticosteroids during the last 28 days before receiving first dose of vaccination against sars-cov-2 and up to subject enrolment. - subjects who, for any reason, did not receive the 2nd dose of the anti-sars-cov-2 mrna vaccine. - subjects that received the 3rd dose of anti-sars-cov-2 mrna vaccine prior to study entry. - subject that received any dose of non-mrna anti-sars-cov-2 vaccine platform. - known prior severe hypersensitivity to anti-sars-cov-2 mrna vaccines or any component in its formulations.

- known pregnant and/or lactating women. - subject with a significant medical, neuro-psychiatric, or surgical condition, currently uncontrolled by treatment, which, in the principal investigator's opinion, may interfere with completion of the study. - subjects with active diagnosis of acute leukaemia. - subjects treated with bone marrow transplant < 90 days before received vaccination against sars-cov-2. - subjects with a known history of hiv infection. - covid-19 infection in the last 28 days before receiving first dose of vaccination against sars-cov-2 and up to subject enrolment. - subjects receiving prolonged and/or high doses of systemic immunosuppressive therapies including corticosteroids during the last 28 days before receiving first dose of vaccination against sars-cov-2 and up to subject enrolment. - subjects who, for any reason, did not receive the 2nd dose of the anti-sars-cov-2 mrna vaccine. - subjects that received the 3rd dose of anti-sars-cov-2 mrna vaccine prior to study entry. - subject that received any dose of non-mrna anti-sars-cov-2 vaccine platform. - known prior severe hypersensitivity to anti-sars-cov-2 mrna vaccines or any component in its formulations.