Inclusion Criteria:  Age ≥ 18 years old ECOG performance status ≤ 2  Must have histologically or cytologically confirmed cancer diagnosis (invasive solid tumour or haematological malignancy)  currently undergoing active systemic cancer treatment (such as chemotherapy, immunotherapy, targeted agents, endocrine therapy) in non-metastatic setting or in metastatic setting (1st line therapy at the time of 1st dose of the anti-SARS-CoV-2 mRNA vaccine) or currently undergoing follow-up after confirmed cancer complete remission without active cancer treatment for the last 12 months Life expectancy > 6 months Received 2nd dose of mRNA platform vaccination against SARS-CoV-2 as per local guidelines within 6 months (maximum until 6 months and 3 weeks) prior to registration. Urine pregnancy test negative for all female subjects of childbearing potential within 7 days prior to subject enrolment. Signed Informed Consent form (ICF) obtained prior to any study related procedure. Subject is willing and able to comply with the protocol for the duration of the study including treatment and scheduled visits and examinations.  Exclusion Criteria:  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.