The course of patients with hairy cell leukemia during the omicron surge of the Covid-19 pandemic.

In this study, we aim to explore the outcomes of Covid-19 infection in patients with Hairy cell leukemia (HCL). The cohort is based on data obtained from electronic medical records. It includes 218 consecutive patients diagnosed with HCL between 16 June 1998, and 20 September 2022, out of which the coronavirus has infected 85 patients during the Omicron surge. Out of 85 patients with HCL who were infected by Covid-19; 7 patients (8.2%) have been hospitalized, and the mortality rate was 2.3% (two patients). Thirteen of the 85 patients had been infected by Covid-19 in previous waves, including 9/13 after vaccination, and none of them developed a severe disease. Humoral immune response after three doses of the BNT162b2 mRNA vaccination regimen was evaluated in 40 patients and was attained in 67.5%. Based on multivariate analysis: unfavorable outcome was significantly more common in patients with HCL above 65 years old, who had at least one cytopenia, and with comorbidity of cardiovascular disease or asplenia. Our results indicates that the course of COVID-19 in patients with HCL during the Omicron wave has been improved relatively favorable.