Impact of respiratory syncytial virus infection among patients with hematological cancer in the era of post-coronavirus pandemic.

400 Background: Two vaccine is recently approved for elderly patient with compromised immunity. Despite the recommendation by Center for Disease Control and Prevention (CDC), RSV vaccination is remains low among patient with hematological malignancy, when compare to influenza vaccination. Thus, we conducted an observational study to estimate the impact of RSV infection among patients with hematological malignancy. Methods: We conducted a population-based retrospective cohort utilized the TritNetx dataset, which consist of patients across 63 U.S. healthcare organization. This study included patient who had respiratory viral infection after a diagnosis of hematological malignancy during 6/1/2022 - 4/1/2022. Hematological malignancy was identified using ICD-10 codes. CPT code and ICD-10 code were used to identify diagnosis of respiratory viral infection after respiratory pathogen panel testing. Patient who was diagnosed with RSV, influenza or COVID-19 were paired based on the following variable, including demographics, body mass index, comorbidities, and anti-neoplastic therapy. Hazard ratio (HR) was estimated by Cox proportional hazard regression models and log-rank test. Risk ratio (RR) was calculated by logistic regression. Results: A total of 6,088 patients with hematological malignancy contracted RSV, influenza or COVID during the observation period. When compare to influenza, patients with RSV infection were associate with high healthcare utilization, including emergency visit (HR: 1.20, 95% CI:[1.00-1.41]), and hospitalization (HR: 1.29, 95% CI:[1.06-1.57]). RSV infection was also resulted in higher acuity including viral pneumonia (HR: 15.42, 95% CI:[9.26-25.68]), use of antibiotics (HR: 1.54, 95% CI:[1.28-1.86]), renal replacement therapy (HR: 2.09, 95% CI:[1.10-3.96]), and acute respiratory failure (HR: 1.54, 95% CI:[1.14-2.07]). When compare to COVID-19, RSV infection showed similar trend including more frequent emergency visit (HR: 1.30, 95% CI:[1.10-1.54]), and high risk of developing viral pneumonia (HR 23.48, 95% CI: [12.79-43.09]). Interestingly, the intubation rate, 28 days all-cause mortality and 90 days all-cause mortality were similar between the three cohort. Conclusions: RSV infection was associated with higher rate of pneumonia and healthcare utilization. RSV vaccination should be considered to prevent RSV-associated morbidity among patients with hematological malignancy.