Can a child catch pneumonia in a household where viral pneumonia is present?

Yes: Keep children away from sick people. Take it as an opportunity to teach good hygiene practices. Wash hands, cover your cough, use clean utensils and tools ...Etc.

Possibly: Viral respiratory infections are generally contagious through air born droplets or oral secretions. A reasonable attempt to isolate the patient from vulnerable kids is worthwhile.Most adults will be at least partially immune due to their own childhood illnesses.