Prevalence and clinical outcomes of respiratory syncytial virus, COVID-19, and influenza among older hospitalized adults: the EVERY prospective cohort study

OBJECTIVES: The impact of respiratory syncytial virus (RSV) among older adults hospitalized for acute respiratory symptoms was uncertain. We compared the prevalence and clinical outcomes of RSV with those of COVID-19 and influenza in older adults hospitalized for acute respiratory symptoms. METHODS: We conducted a multicentre prospective cohort study at three community hospitals, which enrolled emergently hospitalized adults aged ≥50 years with acute respiratory symptoms or signs from July 1, 2023, to December 31, 2024. RSV, COVID-19, and influenza A/B were measured using the FilmArray Respiratory panel 2.1 on a nasopharyngeal swab. The primary outcomes were lower respiratory tract infections (LRTIs), defined as presence of ≥2 lower respiratory symptoms/signs for at least 24 hours, including ≥1 lower respiratory sign or presence of ≥3 lower respiratory symptoms for at least 24 hours; modified LRTIs, incorporating chest radiography or computed tomography; and the 30-day all-cause mortality. RESULTS: During the 18-month study period, 3067 patients were included, with a mean age of 81 years (standard deviation: 11), and 55% of whom were male. Comorbidities included chronic pulmonary diseases (28%), chronic heart failure (32%), and diabetes (30%). The vaccination rates for RSV, COVID-19, and influenza were 0%, 62.3%, and 37.9%, respectively. The prevalence of RSV, COVID-19, and influenza A/B was 1.6%, 18.0%, and 2.3%, respectively. The rates of LRTIs were 87.8% (RSV), 82.8% (COVID-19), and 88.4% (influenza A/B). The rates of modified LRTIs exhibited a marginal increase. The 30-day mortality was highest among patients with RSV (14.3%) compared with those with COVID-19 (8.4%) and influenza A/B (2.9%) (p = 0.02). The adjusted odds ratios (95% confidence intervals) of 30-day mortality with RSV and COVID-19 relative to influenza A/B were 5.2 (1.2-36.7) and 2.9 (0.83-17.9), respectively. CONCLUSIONS: RSV should be recognized as a risk factor for mortality among older adults emergently hospitalized for acute respiratory symptoms.