The main objective of this study is to investigate the humoral immune response to COVID-19 vaccines in haematological patients, by testing SARS-CoV-2 seroconversion

This single-center prospective study will enroll approximately 700 hematologic patients who access to Haematological Division (San Gerardo Hospital, Monza, Italy) in order to perform their routine blood tests to monitor their hematological conditions. Evaluation of Sars-Cov-2 IgG specific antibodies will be performed on left-over biological material (serum or plasma) collected during routine blood tests run between 30 and 60 days after the administration of the second vaccine dose.

Furthermore, in each patient who has failed seroconversion (absence of specific antibodies for circulation), his cellular immune response will be assessed using an additional blood sample collected during routine blood tests.

These samples will be collected within 9 months of the completion of the vaccination series and will be used to evaluate the plasma INF-γ release using QuantiFERON SARS-CoV-2 test.

Inclusion Criteria:

• Signed and dated EC-approved informed consent
• Hematological disease defined according to World Health Organization (WHO) criteria
• Female or male, 18 years of age or older
• ECOG performance status 0-3
• Willingness and ability to comply with routine clinical practice and study procedures
• Regular vaccination against SARS-CoV-2 according to Italian Haematological Society (SIE) guidelines/recommendations (Version 2.0, 20 April, 2021).
• Routine blood test planned between 30 and 60 days after administration of the second vaccine dose according to regular hematological follow up.
• Routine blood test planned no later than 9 months after the completion of the vaccination series (only in case of absence of circulation specific antibodies).

Exclusion Criteria:

• Preventive vaccination against SARS-CoV-2 not administered according to Italian Haematological Society (SIE) guidelines/recommendations (Version 2.0, 20 April, 2021)
• Evidence of previous infection with the SARS-Cov-2 virus.
• Routine blood test not planned between 30 and 60 days after administration of the second vaccine dose.
• Routine blood test not planned within 9 months after the completion of the vaccination series (only in case of absence of circulation specific antibodies).

Haematological patients followed at the Haematological Division, San Gerardo Hospital, Monza, Italy