Thrombotic and bleeding complications in patients with chronic lymphocytic leukemia and COVID-19: A study of ERIC, the European Research Initiative on CLL (preprint)

Background: Patients with chronic lymphocytic leukemia (CLL) may be more susceptible to COVID-19 related poor outcomes, including thrombosis and death, due to the advanced age, the presence of comorbidities, and the disease and treatment-related immune deficiency. In this retrospective multicenter study, conducted by ERIC, the European Research Initiative on CLL, we assessed the risk of thrombosis and bleeding in patients with CLL affected by severe COVID-19.Methods: The study included patients from 79 centers across 22 countries. Data collection was conducted between April and May 2021.Results: A total of 793 patients from 79 centers were included in the study with 593 being hospitalized (74.8%). Among these, 518 were defined as having severe COVID: 162 were admitted to the ICU while 356 received oxygen supplementation outside the ICU. Most patients (90%) were receiving thromboprophylaxis. During COVID-19 treatment, 8.8% developed a thromboembolic event, while 4.8% experienced bleeding. Thrombosis developed in 20.5% of patients who were not receiving thromboprophylaxis, but only in 8.1% of patients who were on thromboprophylaxis. Bleeding episodes were more frequent in patients receiving intermediate/therapeutic versus prophylactic doses of low-molecular-weight heparin (LWMH) (11.1% vs. 4.2%, respectively) and in elderly. In multivariate analysis, peak D-dimer level was a poor prognostic factor for thrombosis occurrence (OR=1.020, 95%CI 1.006‒1.033), while thromboprophylaxis use was protective (OR=0.194, 95%CI 0.061‒0.614). Age and LMWH intermediate/therapeutic dose administration were prognostic factors in multivariate model for bleeding (OR=1.055, 95%CI 1.013-1.103 and OR=2.490, 95%CI 1.044-5.935, respectively). Conclusions: Patients with CLL affected by severe COVID-19 are at a high risk of thrombosis if thromboprophylaxis is not used, but also at increased risk of bleeding under the LMWH intermediate/therapeutic dose administration.  

Diagnosis and Tracking of Past SARS-CoV-2 Infection in a Large Study of Vo', Italy Through T-Cell Receptor Sequencing (preprint)

Measuring the adaptive immune response after SARS-CoV-2 infection may improve our understanding of COVID-19 exposure and potential future protection or immunity. We analyzed T-cell and antibody signatures in a large population study of over 2,200 individuals from the municipality of Vo', Italy, including 70 PCR-confirmed COVID cases (24 asymptomatic, 37 symptomatic, 9 hospitalized). Blood samples taken 60 days after PCR diagnosis demonstrated 97% (68/70) of the latter subjects had a positive T-cell test result, higher than an antibody serology assay (77%; 54/70 of subjects) performed on the same samples. The depth and breadth of the T-cell response was associated with disease severity, with symptomatic and hospitalized COVID cases having significantly higher response than asymptomatic cases. In contrast, antibody levels at this convalescent time point were less informative as they did not correlate with disease severity. 45 additional suspected infections were identified based on T-cell response from the 2,220 subjects without confirmatory PCR tests. Among these, notably, subjects who reported symptoms or had household exposure to a PCR-confirmed infection presented a higher T-cell test positive rate. Taken together, these results establish that T cells are a sensitive, reliable and persistent measure of past SARS-CoV-2 infection.