Subjects meeting one of the following criteria are not eligible for this study: 1) Known pregnant and/or lactating women. 2) 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. 3) Subjects with active diagnosis of acute leukaemia. 4) Subjects treated with bone marrow transplant < 90 days before received vaccination against SARS-CoV-2. 5) Subjects with a known history of HIV infection. 6) COVID-19 infection in the last 28 days before receiving first dose of vaccination against SARS-CoV-2 and up to subject enrolment. 7) 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.8) Subjects who, for any reason, did not receive the 2nd dose of the anti-SARS-CoV-2 mRNA vaccine. 9) Subjects that received the 3rd dose of anti-SARS-CoV-2 mRNA vaccine prior to study entry. 10) Subject that received any dose of non-mRNA anti-SARS-CoV-2 vaccine platform. 11) Subjects 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. 12) Subjects who have received any other licensed vaccines for other indications within 28 days prior to the 3rd dose, or who are planning to receive any other vaccine up to 14 days after the 3rd dose of the mRNA anti-SARS-CoV-2 vaccine (28 days for live attenuated vaccines). For influenza vaccination, a shorter interval or simultaneous administration is acceptable.

Subjects meeting one of the following criteria are not eligible for this study: 1) Known pregnant and/or lactating women. 2) 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. 3) Subjects with active diagnosis of acute leukaemia. 4) Subjects treated with bone marrow transplant < 90 days before received vaccination against SARS-CoV-2. 5) Subjects with a known history of HIV infection. 6) COVID-19 infection in the last 28 days before receiving first dose of vaccination against SARS-CoV-2 and up to subject enrolment. 7) 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.8) Subjects who, for any reason, did not receive the 2nd dose of the anti-SARS-CoV-2 mRNA vaccine. 9) Subjects that received the 3rd dose of anti-SARS-CoV-2 mRNA vaccine prior to study entry. 10) Subject that received any dose of non-mRNA anti-SARS-CoV-2 vaccine platform. 11) Subjects 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. 12) Subjects who have received any other licensed vaccines for other indications within 28 days prior to the 3rd dose, or who are planning to receive any other vaccine up to 14 days after the 3rd dose of the mRNA anti-SARS-CoV-2 vaccine (28 days for live attenuated vaccines). For influenza vaccination, a shorter interval or simultaneous administration is acceptable.