Viral respiratory infections in patients with hematological diseases over 10 years: epidemiology and impact on disease severity

Objectives: Respiratory viral infections (RVI) can worsen outcomes or delay treatment delivery in patients with hematological diseases (HD). Methods: This is a retrospective, single-center, observational study on respiratory viral infection (RVI) episodes identified over a 10-year period in consecutive HD patients. Respiratory viruses were detected by the respiratory viral panel multiplex-PCR (Allplex, Seegene Inc.) according to clinical practice. Repeated positive samples without evidence of negative tests in between were grouped into a single infection episode. Logistic regression models defined factors associated with severe clinical outcomes. Results: Of the 4,136 respiratory samples collected from 1,434 HD individuals, 837, corresponding to 522 distinct episodes, were positive for at least one respiratory virus. 478 (91.6 %) episodes involved a single virus infection. Of note, 245 (46.9 %) occurred in patients receiving allogenic stem cell transplant (HSCT). Most episodes occurred in winter (236 cases, 45.2 %), vs. in spring (125, 23.9 %) or in autumn (123, 23.6 %). Among RVIs, Rhinovirus (n = 264, 50.6 %) was the most common, while Influenza (n = 74, 14.2 %), RSV (n = 55, 10.5 %), and Coronaviruses (n = 52, 10.0 %) were less frequent. The 10 longest persistence RT-PCR positivity were observed with Rhinoviruses. Logistic regression models showed that RSV positivity, advanced age, inpatient status and HSCT were all positively associated with severe outcomes (P < 0.05). Conclusions: This study confirms that RVIs are common in HDs, with the highest prevalence observed in winter. RSV was significantly associated with progression to severe outcomes. These results underscore the importance of implementing effective prophylaxis and control strategies for respiratory viruses, particularly in immunocompromised settings.