Mortality Risk Rises 2.7-Fold in Adults After Respiratory Syncytial Virus

Presented at the European Society of Clinical Microbiology and Infectious Disease (ESCMID) Global 2025 Congress, a recent study from Denmark indicated that adults suffering from respiratory syncytial virus-associated acute respiratory infection (RSV-ARI) have a risk of mortality 2.7-fold higher than that of a healthy person.1,2

RSV-ARI refers to a collection of illnesses caused by respiratory syncytial virus, which is common and extremely contagious. Although its impact on children and infants has been widely studied, the extent of its burden on adults is poorly understood.2

"Exacerbations of chronic obstructive pulmonary disease (COPD) and asthma were the most common adverse clinical outcomes. These pre-existing conditions are already challenging in themselves, and RSV-ARI exacerbates their severity,” said lead author Maria João Fonseca, PhD, associate director of Global Real World Evidence and Health Outcomes, Vaccines at GSK.1 "Because of this, it’s crucial that we pay closer attention to patients with these underlying conditions to prevent further, potentially life-threatening complications."

The initial purpose of the study was to examine economic and clinical outcomes for RSV-ARI patients, as well as the capability of the Danish healthcare industry to provide the necessary vaccines. Investigators included all Danish individuals ≥18 years with either a positive laboratory test for RSV or an RSV-ARI-coded hospital contact between 2011 and 2022.1

Clinical and economic outcomes were assessed up to 30, 60, 90, and 365 days after onset of RSV-ARI. Investigators then matched cases 1:3 with individuals from the general population with no ARI history during the inclusion period.1

In total, the study included 5289 RSV-ARI cases and 15,867 controls. Participants had a mean age of 63 years, and 57% were female. The most common comorbidities included COPD (24%), diabetes (13%), and asthma (12%). Additionally, 32% of individuals were immunocompromised.1

Upon analysis, the individual risks of every negative clinical outcome rose among RSV-ARI patients compared to controls from 30 days to 365 days of follow-up. During the final follow-up at 365 days, investigators discovered that mortality was 2.7-fold higher than control (13.0% vs 4.8%), while COPD and asthma exacerbations were 3.1- and 4.6-fold higher, respectively (55.7% vs 18.3% and 24.1% vs 5.2%) (all P <.001).1

Of the RSV-ARI patients, 57% were hospitalized and 5.3% required intensive care, compared to 28% and 1.4% of controls, respectively. Approximately 0.3% and 3.1%, respectively, had no healthcare contact.1

In accordance with the study’s initial goals, the team also reported the economic impact of the virus in Denmark. Total direct healthcare costs for RSV-ARI patients reached €20,181 ($22,986 USD). This cost was almost double the €8085 ($9221 USD) paid for the control group.1

Noting the steps required to lower the impact of RSV-ARI, investigators pointed to the highly effective role of vaccination in preventing severe outcomes from RSV.

“Given the significant burden of RSV-ARI highlighted by our study, prioritising vaccination for vulnerable populations is essential to reduce both health complications and associated costs," said co-author Stanislava Bratković, MD, Medical Advisor for Vaccines, GSK, to ESCMID Global. “Looking forward, we hope our findings will inspire further research into the broader clinical and societal burden of RSV, particularly in high-risk groups."

References

1. Fonseca, M. J., Bratković, S., et al. (2025). Clinical and economic burden of respiratory syncytial virus in adults with acute respiratory infections – a Danish nationwide cohort study. Oral presentation. ESCMID Global 2025.

2. BEYOND. Common respiratory condition nearly triples the risk of death in adults, new study finds. Eurekalert! April 11, 2025. Accessed April 10, 2025.