Respiratory Viral and Bacterial Superinfection.

Respiratory viral infections are major predisposing factors for secondary bacterial pneumonia, a complication associated with increased disease severity, prolonged hospitalizations, and higher mortality. This review discusses the key mechanisms by which viral infections disrupt lung physiology, impair innate and adaptive immune defenses, and dysregulate cytokine signaling, creating a permissive environment for bacterial superinfection. Common pathogenic processes across different respiratory viruses are highlighted to provide a comprehensive understanding of how viral infections alter host susceptibility to bacterial pneumonia.