Respiratory Syncytial Virus Exceeded SARS-CoV-2 and Influenza in Lower Respiratory Infection and Mortality Rates Among Patients With Hematologic Malignancies During the 2023-2024 Respiratory Virus Season.

BACKGROUND

Respiratory viral infections (RVIs) significantly impact patients with hematologic malignancies (HMs). During the 2023-2024 respiratory viral (RV) season, we observed a decline in SARS-CoV-2-related hospitalizations in our center compared to the two previous seasons. Given the changing epidemiology of RVIs in the post-pandemic era, the low acceptance of SARS-CoV-2 and influenza vaccination, and the availability of new respiratory syncytial virus (RSV) vaccines in 2023, we aimed to compare outcomes of RSV, influenza, and SARS-CoV-2 infections in patients with HMs during the 2023-2024 RV season.

METHODS

We retrospectively analyzed adults with HMs diagnosed with RSV, influenza, or SARS-CoV-2 between October 2023 and April 2024. The primary outcomes were lower respiratory tract infection (LRI), hospitalization, and 30-day all-cause mortality.

RESULTS

We identified 503 patients with 536 consecutive RVIs: 50.0% with SARS-CoV-2, 26.1% with RSV, and 22.2% with influenza (1.7% co-infections). Among RSV-infected patients, 50.7% developed LRI, compared to 41.2% with influenza and 39.2% with SARS-CoV-2 (p = 0.076). The 30-day all-cause mortality was 9.3% for RSV, 7.6% for influenza, and 3.4% for SARS-CoV-2 (p = 0.037). In the multivariable analysis, RSV was associated with higher LRI rate compared to SARS-CoV-2, along with older age, refractory/relapsed cancer, nosocomial infections, and lymphopenia. Older age, allogeneic hematopoietic cell transplantation, nosocomial infections, and LRIs were associated with increased mortality.

CONCLUSIONS

During the 2023-2024 RV season, the clinical impact of these viruses on patients with HMs remains significant, with higher morbidity and mortality from RSV, highlighting the persistent unmet need for better management strategies for RVIs in the post-pandemic era.