Prolonged SARS-CoV-2 infection in hematologic malignancies: clinical impact, risk factors and intra-host viral evolution.

Introduction: Prolonged SARS-CoV-2 infection in hematologic patients may go unrecognized. The aim of the study is to describe the incidence, risk factors, viral evolution and clinical outcomes of prolonged SARS-CoV-2 infection in patients with hematologic malignancies. Methods: This is a prospective, observational study. We performed a longitudinal follow-up rRT-PCR with cycle threshold (Ct) assessment until negativization to 500 patients diagnosed with hematologic malignancies who suffered SARS-CoV-2 infection between March 2020 and August 2023. We considered prolonged COVID-19 to a positive rRT-PCR with a Ct <35 beyond 30 days after microbiological diagnosis with the same viral variant. Results: Prolonged SARS-CoV-2 infection is a complication in 44.8% (156/348) of patients diagnosed with hematologic malignancies with a median time of rRT-PCR positivity of 58 days (IQR 43-88). Active treatment with bispecific antibodies, anti-CD20 antibodies, BTK inhibitors and immunosuppressive drugs for GvHD are significantly associated with prolonged viral shedding; as well as lack of vaccination, lesser booster vaccine doses, absence of anti-S seroconversion after immunization, severe acute infection and delayed antiviral treatment. A 56.4% (88/156) of patients exhibit a pattern of remitting and relapsing symptoms and fluctuant viral load. During those exacerbations, 70.5% of patients experienced an increase in the severity of the acute infection and 34% developed pneumopathy, particularly organizing pneumonia. Persistent COVID-19 caused 54.5% (85/156) of patients to interrupt and 19.9% (31/156) to suspend indefinitely their hematologic treatments. Viral intra-host mutations across the entire viral genome, predominantly within the spike were detected in most patients with prolonged COVID-19, especially in those who received anti-SARS-CoV-2 mAb as sotrovimab (E340, R346, K356) and tixagevimab/cilgavimab (R346, K444 and G446). These substitutions are associated with reduced viral susceptibility. Discussion: Prolonged SARS-CoV-2 infection in hematologic patients is frequent and leads to persistent viral replication, significant morbidity and the emergence of intra-host viral mutations. Optimizing treatments and monitoring viral clearance are medical needs for high-risk patients.