Community-Acquired Respiratory Virus Infections: A Threat to Long-Term Survivors After Allogeneic Stem Cell...

Studies on late community-acquired respiratory virus (CARV) infections in long-term allogeneic hematopoietic stem cell transplantation (allo-HCT) survivors are scarce, creating knowledge gaps on the epidemiology, risk of progression to lower respiratory tract disease (LRTD), and conditions linked to poor outcomes.

We included consecutive CARV infection episodes occurring up to 6 months after allo-HCT registered in our database from December 2013 to June 2023 at 2 Spanish transplant centers.

Among 426 allo-HCT recipients, 1070 CARV episodes were recorded, 791 (74%) with only upper respiratory tract disease (URTD) and 279 (15%) progressing to LRTD, at a median of 18.6 months post-transplant. The most common CARVs were rhinovirus, respiratory syncytial virus (RSV), and influenza. The LRTD progression rate was 26%, with a 4.9% all-cause mortality rate at 100 days post-CARV detection. Risk factors for LRTD progression included graft-versus-host disease prophylaxis (odds ratio [OR] 3.08), corticosteroid use (0.1 to <30 mg/day: OR 2.44; ≥30 mg/day: OR 5.19), absolute lymphocyte count (ALC) <1 × 10^9/L (OR 1.60), fever at CARV screening (OR 4.27), RSV (OR 2.46), and human metapneumovirus (HMPV) (OR 2.76). Risk factors for 100-day all-cause mortality included human leukocyte antigen (HLA) mismatch (hazard ratio [HR] 2.49); corticosteroid use (0.1 to <30 mg/day: HR 3.87; ≥30 mg/day: HR 5.77); ALC <1 × 10^9/L (HR 2.44); neutropenia <0.5 × 10^9/L (HR 6.74), and age ≥40 years (HR 4.85).

Recipients with profound and prolonged immunosuppression remain at risk for severe CARV infection outcomes late after allo-HCT, necessitating intensive clinical monitoring for respiratory symptoms.