Adult respiratory syncytial virus infection and community-acquired pneumonia: pathogenesis, diagnostic challenges and the clinical implications

INTRODUCTION: Community-acquired pneumonia (CAP) remains a significant cause of adult morbidity and mortality. Respiratory syncytial virus (RSV) contributes meaningfully to adult CAP, particularly in older adults and those with chronic cardiopulmonary disease, yet is frequently underdiagnosed because clinical features overlap with other respiratory infections and routine testing is limited. AREAS COVERED: This review summarizes key virological and immunological characteristics of RSV, highlights diagnostic challenges in adults, and discusses clinical consequences beyond respiratory illness, including cardiovascular complications, severe in-hospital outcomes, and secondary bacterial infection with antibiotic exposure. Using Korean and international data, we emphasize the value of multi-specimen molecular testing to improve detection and discuss the implications for antimicrobial stewardship in CAP management. We also provide an overview of vaccine efficacy in phase 3 trials and early real-world effectiveness in older adults. EXPERT OPINION: Reducing the adult RSV burden will require a feasible diagnostic pathway during periods of RSV circulation, strengthened surveillance that captures clinically meaningful outcomes, and targeted vaccination of high-risk populations. Ongoing post-authorization evaluation and research in immunocompromised and other high-risk groups are needed to optimize vaccination strategies and inform next-generation prevention.