New research challenges the assumption that human rhinovirus is a direct cause of pneumonia in adults, providing evidence that rhinovirus can infect the lower lungs and independently drive pneumonia.

By Ada Enesco


RT’s Three Key Takeaways:

  1. Rhinovirus as a pneumonia pathogen – New clinical and histological evidence shows that human rhinovirus can directly infect the lower respiratory tract and independently cause pneumonia in hospitalized adults, overturning the belief that it is limited to upper airway disease.
  2. Prevalence and risk factors – Rhinovirus was detected in 4.6% of hospitalized adults, with over half developing pneumonia, and male sex, fever, and cough identified as independent predictors of rhinovirus-associated pneumonia.
  3. Clinical significance – Rhinovirus should no longer be dismissed as a benign bystander in adult pneumonia, as recognizing its role could improve diagnosis, infection control, and future antiviral research, especially during peak seasonal circulation.


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 hospitalized 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.

This article was originally published by EMJ and was made available under the terms of the Creative Commons Attribution-Non Commercial 4.0 License.