A cohort study found that approximately 5% of adults diagnosed with respiratory syncytial virus in outpatient settings were hospitalized within 28 days. The research, which spanned 6 RSV seasons from 2016 to 2022, highlighted the substantial burden of respiratory syncytial virus among adults, particularly those who are older or have chronic medical conditions.

In the study, published in JAMA Network Open, investigators from Pfizer and collaborators analyzed data from three large de-identified U.S. databases containing electronic health records linked to closed insurance claims. They identified 67,239 outpatient medically attended respiratory syncytial virus (RSV) infections in adults. The overall proportion hospitalized within 28 days ranged from 4.5% to 6.2% across the databases.

Among a high-risk subgroup of adults aged 65 years or older or with chronic obstructive pulmonary disease, congestive heart failure, or asthma, the hospitalization rate was higher—ranging from 6.5% to 8.5%. Other comorbidities associated with increased hospitalization risk included chronic kidney disease, pulmonary fibrosis, cancer, and immunocompromised status.

The investigators noted that RSV vaccines were recently licensed for older adults, but treatment options continue to remain limited. The findings may inform clinical risk assessment and the development of interventions aimed at preventing severe outcomes.

The study's limitations included the reliance on RSV testing, which is not consistently performed. The infections identified likely underrepresented the true burden of RSV in the general population. However, the research represented the largest effort to date to quantify the real-world risk of hospitalization following outpatient RSV diagnosis in adults.

Conflict of interest disclosures can be found in the study.