Rhinovirus and Adult Lower Respiratory Infection: Rethinking a “Common Cold” Virus
HUMAN rhinovirus (HRV) is best known as the leading cause of the common cold, yet its role in serious adult lower respiratory tract infections has long been debated. Traditionally viewed as a pathogen confined to the upper airways, HRV has rarely been considered a direct cause of pneumonia in adults. New research now challenges this assumption, providing compelling clinical and biological evidence that rhinovirus can infect the lower lungs and independently drive pneumonia in hospitalised adults.
How Common Is Rhinovirus in Adult Hospital Admissions?
In this large retrospective study spanning January 2020 to December 2023, researchers analysed over 9,500 hospitalised adults who were screened for HRV using RT-PCR testing. Rhinovirus was detected in 4.6% of patients, with clear seasonal peaks in late winter to early spring and again in autumn. These patterns mirror known community circulation of HRV, reinforcing its relevance beyond mild outpatient illness.
Importantly, nearly half of HRV-positive patients had co-infections, most commonly bacterial pathogens or other respiratory viruses. This finding reflects real-world clinical complexity and helps explain why the contribution of rhinovirus to severe disease has often been underestimated.
Rhinovirus-Associated Pneumonia: Who Is at Risk?
Among the 437 HRV-positive patients, more than half developed pneumonia. However, only a smaller subset met strict diagnostic criteria for “simple” viral pneumonia, where rhinovirus was considered the primary cause rather than a bystander.
Multivariable analysis identified three independent predictors of rhinovirus pneumonia: male sex, fever, and cough. Adults presenting with cough were at particularly high risk, suggesting that clinicians should consider HRV as a potential culprit when evaluating viral pneumonia, especially in men with febrile respiratory illness.
Direct Evidence of Rhinovirus Infection in the Lower Lung
The most significant finding comes from histological analysis. In patients who underwent bronchoalveolar lavage and lung biopsy, immunofluorescence staining detected rhinovirus VP3 protein within lower respiratory tract cells in over 60% of cases examined. This provides the first direct tissue-based evidence that HRV can infect alveolar and lower airway cells in immunocompetent adults.
This discovery resolves a long-standing controversy about whether rhinovirus merely accompanies lower respiratory disease or actively causes it. The findings confirm that HRV has true lower respiratory tract tropism, not just incidental detection in respiratory samples.
Clinical Implications for Adult Respiratory Care
These results have important implications for respiratory medicine and infectious disease practice. Rhinovirus should no longer be dismissed as a harmless contaminant when detected in adults with pneumonia. Instead, it may represent an under-recognised cause of viral lower respiratory tract infection, particularly during peak seasons.
While co-infections remain common, this study shows that rhinovirus can independently drive pneumonia. Improved recognition could influence diagnostic algorithms, infection control measures, and future antiviral research.
Reference
Zhang R et al. Rhinovirus-associated lower respiratory tract infection in hospitalized adult patients: a retrospective cohort study. J Infect Dis. 2025; DOI:10.1093/infdis/jiaf651.
