Hospital Transmission Risk May Be Higher for RSV- vs Influenza-Associated Pneumonia

Severe respiratory syncytial virus (RSV)-associated pneumonia infection may be transmissible than severe influenza virus-associated pneumonia infection in hospital settings. These study results were published in Open Forum Infectious Diseases.

This prospective study was conducted among adults with severe pneumonia at a tertiary care hospital in Seoul, South Korea between March 2010 and February 2019. Eligible patients (n=2,865) were those aged 16 years and older with severe RSV- or influenza virus-associated pneumonia infection who required intensive care unit (ICU) admission. Patients in both groups were monitored until the occurrence of mortality or hospital discharge. Researchers compared clinical characteristics and mortality outcomes between the groups. Survival was assessed via Cox proportional hazards analysis, and risk factors for 90-day mortality were assessed via multivariate regression.

There were 2865 patients included in the analysis, of whom 94% had community- and 67.2% had hospital-acquired infection. Among 747 patients with severe viral pneumonia infection, 174 (23.3%) had influenza virus-associated pneumonia and 102 (13.6%) had RSV-associated pneumonia. Overall, the most common viral pathogens were influenza virus (6.1%), rhinovirus (5.7%), parainfluenza virus (4.4%), and RSV (3.6%).

Further analysis was performed after the exclusion of patients coinfected with severe RSV- and influenza virus-associated pneumonia. Of the remaining patients in the RSV (n=92) and influenza groups (n=163), the median ages were 65.0 and 68 years, and 55.4% and 60.7% were men. In addition, hematologic malignancies (32.6% vs 14.1%) and immunocompromised status (57.6% vs 34.4%) were more commonly observed among patients in the RSV vs influenza groups (32.6% and 14.1%).

The researchers noted significantly higher rates of community-acquired pneumonia among patients in the influenza vs RSV groups (41.7% vs 21.7%; P =.001), whereas patients in the RSV group had significantly higher rates of hospital-acquired pneumonia (47.8% vs 23.9%; P <.001). However, no significant between-group differences in the site of acquisition were found after immunocompromised patients were excluded.

The seasonality of RSV infection was similar to that of influenza virus infection, with both diseases peaking in January and February. Overall, clinical symptoms were not associated with specific viral pathogens, though more patients in the RSV vs influenza groups reported cough (60.9% vs 75.3%; P =.02).

The rate of 90-day mortality was similar between patients with severe RSV- vs influenza virus-associated pneumonia (43.5% vs 40.5%; P =.89). Risk factors for 90-day mortality included immunocompromised status (adjusted hazard ratio [aHR], 2.08; 95% CI,1.43–3.01]; P <.001), an Acute Physiology and Chronic Health Evaluation (APACHE) II score of at least 25 at ICU admission (aHR, 2.43; 95% CI, 1.60–3.67; P <.001), and lack of radiographic improvement within 72 hours (aHR, 2.00; 95% CI, 1.22–3.29; P =.01).

For patients with severe RSV-associated pneumonia, risk factors 90-day mortality included a platelet count of 100,000/mm³ or less (aHR, 2.04; 95% CI, 1.08-3.83; P =.03), as well as an APACHE II score of at least 25 at hospital admission (aHR, 2.56; 95% CI, 1.17-5.59; P =.02).

Limitations of this study include its single-center and observational design, the inability to assess viral genotypes, and the exclusion of patients who did not require ICU admission.

“This finding of a relatively higher incidence of severe RSV-associated pneumonia in healthcare settings than in the community suggests that there might be increased transmissibility of RSV in hospital settings,” the researchers noted. “Constant awareness of the possibility of RSV infection and timely infection control measures for RSV are essential, especially in immunocompromised patients,” they concluded.

This article originally appeared on Infectious Disease Advisor