At the beginning of the COVID-19 pandemic in Europe, it was identified that patients with red blood cell disorders, such as sickle cell anemia and thalassemia, might be at higher risk of serious complications due to their comorbidities. Due to the lack of information, a study was initiated in April 2020 within the framework of the European platform ERN-EuroBloodNet to collect data and support the clinical management of these patients. This work was co-led by two researchers from the Childhood Cancer and Hematological Diseases group at the Vall d'Hebron Research Institute (VHIR).

The ERN-EuroBloodNet study, published in the Orphanet Journal of Rare Diseases, was an innovative tool at the beginning of the pandemic, designed to share knowledge in real time. Its data were presented at international conferences, and although its usefulness diminished after the end of the pandemic and the relaxation of screening policies, it enabled the compilation of the largest European registry of these patients: 681 infections in 663 people. The main objective of the platform was to create a repository with updated data on the impact of COVID-19 on this population so that specialists across Europe could use this information to make policy and strategic decisions, given the lack of literature on the subject.

Various studies have shown that the incidence of COVID-19 in patients with red blood cell disorders was low (between 0 and 2.4%), with mostly mild cases, although some severe. Mortality rates ranged from 0 to 10% for sickle cell anemia and from 0 to 20% for thalassemia. The study led by Vall d'Hebron sought to analyze the incidence and progression of COVID-19 in patients with red blood cell disorders in Europe and identify risk factors for severe cases. It was the study with the largest number of patients with this type of pathology.

The results showed that the incidence of COVID-19 was low compared to the general European population, possibly due to greater adherence to preventive measures. Most cases were mild (92%), and the course of the virus in patients with red blood cell disorders followed the general pattern of variants. Vaccination showed positive effects, with an immunization rate similar to that of the general population (32%).

Twenty-two percent were hospitalized, 3.7% were admitted to the ICU, and mortality was low (0.7%), lower than that reported in other registries, which could be attributed to intensive medical monitoring. Symptoms were similar to those of the general population, although complications such as acute chest syndrome, kidney failure, and coinfections were associated with greater severity.

“Risk factors for severe disease included hypertension, overweight, and the presence of comorbidities. More cases were also observed in adults with thalassemia, while children between 1 and 10 years of age tended to develop milder symptoms,” explains Dr. Mar Mañú, principal investigator of the Cancer and Pediatric Hematological Diseases group at VHIR.

“The study provides valuable data on the impact of COVID-19 on patients with red blood cell disorders and confirms that specialized care can reduce risks. Furthermore, the registry structure could serve as a model for future health emergencies in Europe,” concludes Dr. Pablo Velasco, attending physician at the Pediatric Oncology and Hematology Department at Vall d'Hebron University Hospital and principal investigator of the Childhood Cancer and Hematological Diseases group at VHIR.

This study builds on the work on the COVID-19 registry in pediatric cancer patients, also led by Vall d'Hebron. Both projects position the hospital as a benchmark in the response to the pandemic in the field of pediatric oncology and hematology.