Final answer:
The primary viral agents that cause viral pneumonia include influenza viruses, parainfluenza virus, respiratory syncytial virus, adenovirus, and SARS coronavirus; these tend to affect the very young and the elderly the most.
Step-by-step explanation:
The viral agents known to cause viral pneumonia as their primary disease include influenza viruses types A and B, parainfluenza virus, respiratory syncytial virus (RSV), adenovirus, and SARS coronavirus. Viral pneumonia often affects children and the elderly, and while many viral respiratory infections tend to be mild and self-limiting, viral pneumonia can lead to more severe illnesses.
Influenza viruses can cause significant morbidity and mortality, especially during annual epidemics. RSV is particularly dangerous for infants, and while most adults recover without intervention, RSV infections in young children can be life-threatening. Unlike bacterial pneumonia, there are fewer specific treatments for viral pneumonia, and care is often supportive.