The overall purpose of this project is to better understand the epidemiology of COVID-19 in patients with hematological malignancies (including hematopoietic stem cell transplant recipients) in the different European Countries. The results obtained will allow us to better know the prevalence of this complication in the different categories of patients with hematological malignancies (HMs). In order to attain the objectives previously described we will develop a multicentre, international, observational, retrospective and prospective study of consecutive cases of COVID-19 among HMs. There will be a clinical follow-up of the patients included in this study to observe the survival rate. Data collected form this study will be evaluated with a descriptive analysis.

At the moment, few data on the epidemiology of SARS-CoV-2 infection in patients suffering from hematological malignancies are available. However, the COVID-19 pandemic presents unique challenges and opportunities on hematological malignancies. The future trajectory of this pandemic appears to be growing and hematology communities must continue to prepare for its spread In this project, we will implement cooperation between all members of the hematology departments both within the EHA and outside it, in order to evaluate the epidemiological data on the incidence and outcome in patients with hematological malignancies infected with SARS-CoV-2.

We will provide useful information to inform the individualized plan for patients with hematological malignancies.

We aim to evaluate the epidemiology and outcomes of patients with HM infected with COVID-19,estimate the incidence and type of disease, assess the acute and long-term mortality rate and estimate the overall mortality rate of cases.

This is a cohort retrospective/prospective survey. In the retrospective phase of the study, participating centers will retrospectively review episodes of COVID-19 disease that occurred in patients with hematological malignancies identified at their institutions from February 2020 to December 2020. In the prospective phase of the study, the researchers will include episodes of COVID-19 disease from the start of the study through December 31, 2021.

The study population will need to be over 18 with hematological malignancies and SARS-CoV-2 An electronic database with anonymization will be created and available to collect all information with single access for each participating institution. The data collected will be demographic data,epidemiological factors, admission information, COVID-19 disease severity, history of hematological malignancies, disease status with past / current treatments, and 30 days of diagnosis.

Inclusion Criteria:

• Age equal to or greater than 18 years of age.
• History of hematological malignancies (acute leukemias, myelodysplastic syndromes, myeloproliferative neoplasms, lymphomas, myeloma, chronic myeloprolipherative disorders) at any stage/status.
• Active hematological malignancies at any stage/status.
• Diagnosis of hematological malignancy (acute leukemias, myelodysplastic syndromes, myeloproliferative neoplasms, lymphomas, myeloma, chronic myeloprolipherative disorders) at any stage/status.
• SARS-CoV-2 positive test (nasopharyngeal, BAL, fecal), documented by Real-Time Reverse Transcriptase (RT)-PCR Diagnostic Panels.

Exclusion Criteria:

• Hematological diseases, other than hematological malignancies.
• Not tested positive for SARS-CoV-2
• Patients "off therapy" for more than 5 years

No formal sample size is planned for this study because not only the main hypothesis will be assessed. However, this is a multicentre cohort study on a high incident disease, with an elevated expected number of events (death, complications, and co-infections) to be observed. So more than 2000 patients are expected to be included.