Severity of respiratory syncytial virus compared with SARS-CoV-2 and influenza among hospitalised adults ≥65 years

Introduction

Our aim was to estimate the risk of pneumonia, admission to intensive care unit (ICU) or death in individuals ≥65 years old admitted to hospital with RSV, compared to influenza or COVID-19.

Methods

We included hospitalised patients from Severe Acute Respiratory Infection Surveillance in Spain between 2021–2024, aged ≥65 years, laboratory confirmed for RSV, influenza or SARS-CoV-2. Using a binomial regression with logarithmic link, we estimated the relative risk (RR) of pneumonia, ICU admission and in-hospital mortality, in patients with RSV compared to influenza or SARS-CoV-2, adjusting for age, sex, season and comorbidities. We stratified the estimates by vaccination status for influenza or SARS-CoV2.

Results

Among patients unvaccinated for influenza or SARS-CoV-2, those with RSV had similar or lower risk of pneumonia [vs. influenza: RR= 0.91 (95% Confidence Interval: 0.72–1.16); vs. SARS-CoV-2: 0.81 (0.67–0.98)], ICU admission [vs. influenza: 0.93 (0.41–2.08); vs. SARS-CoV-2: 1.10 (0.61–1.99)] and mortality [vs. influenza: 0.64 (0.32–1.28); vs. SARS-CoV-2: 0.56 (0.30–1.04)]. Among the vaccinated, results were largely similar except for a higher risk of ICU admission with RSV [vs. influenza: 2.13(1.16–3.89); vs. SARS-CoV-2: 1.83 (1.02–3.28)]

Conclusions

RSV presented similar or lower intrinsic severity than influenza or SARS-CoV2. Among vaccinated patients, RSV was associated to higher ICU-admission, suggesting the potential for preventive RSV vaccination.