Having as much real-time clinical information as possible on diagnosing and treating COVID-19 patients with other serious and rare pathologies is Vall d'Hebron's objective with the international registry for patients with COVID-19 and rare blood diseases. Patient registries compile anonymised information so that clinical information is available when professionals need to make medical decisions regarding the diagnosis and treatment of future patients. This registry includes information on the clinical evolution of COVID-19 and the associated illnesses that patients develop, along with the treatments used."After we had a case of a child with acute lymphoblastic leukaemia who developed COVID-19-associated cytokine release syndrome and was successfully treated with tocilizumab, we realised how important it was to have international data and allow experts worldwide to freely share their knowledge", recalls Dr. Pablo Velasco, a physician with the Vall d'Hebron Paediatric Oncology and Haematology Department and researcher with the Group for Translational Research in Cancer in Children and Teenagers at the Vall d'Hebron Research Institute (VHIR).In light of this, Vall d'Hebron developed a registry for patients with COVID-19 and rare blood diseases such as sickle cell disease and thalassaemia. "Some 250 patients, from Belgium, Cyprus, Denmark, France, Germany, Greece, Ireland, Italy, the Netherlands, Portugal, the United Kingdom, and Spain are included in the registry", explains Dr. Mar Mañú, principal investigator for the VHIR Group for Translational Research in Cancer in Children and Teenagers, and scientific director at the European Reference Network (ERN) for rare blood diseases, EuroBloodNet. The platform has been developed within the framework of EuroBloodNet, the European Reference Network (ERN) for this type of pathology, in which Vall d'Hebron is a participant. Patients who have blood diseases are at a greater risk for complications associated with COVID-19. Most of them have undergone splenectomies (removal of the spleen) in order to improve their haemoglobin levels, an operation that makes them more vulnerable to bacterial infections and superinfections in the wake of a viral infection. Acute respiratory distress syndrome is often triggered by infections.The registry for COVID-19 patients provides support for everyday medical practice, streamlines interprofessional consultations for more complex cases, and allows observational studies to be carried out on different groups of patients. "We have a registry representative in each of the participating countries who alerts us of cases of COVID-19 that appear in patients with rare blood diseases", adds Dr. Mar Mañú. 35 countries participate in the registry of paediatric oncology patients with COVID-19As for the registry of paediatric patients with cancer and COVID-19, developed by the St. Jude Children's Research Hospital, it includes 758 patients from a total of 35 countries. These are children and adolescents with acute lymphoblastic leukaemia, solid extracranial tumours, tumours of the haematopoietic and lymphoid tissues, and central nervous system tumours who have also contracted SARS-CoV-2. "The primary objective is for the medical community who treat paediatric cancer to have updated information on cases of cancer patients with COVID-19 from around the world", emphasises Dr. Pablo Velasco. In addition to the patient registry, the online platform has a section called COVID Conversations, where different specialists from around the world (among them, since the beginning of the pandemic, the professionals at Vall d'Hebron) hold virtual meetings, share experiences, and discuss their more complex cases. It also has a library section, with resources on COVID-19 and paediatric cancer. "These two registries facilitate sharing crucial knowledge internationally, since the number of patients is relatively low if we limit our knowledge to the experience of just one country", adds Dr. Velasco.