In some cases, yes. Two of the main types of conjunctivitis are contagious - those caused by infection by bacteria or viruses. There is a third main type of conjunctivitis, due to allergy, which cannot be passed from person to person. Conjunctivitis affects people of all ages but is more common in children. The best way to avoid infection is to wash hands frequently and avoid sharing towels with someone who has an infectious conjunctivitis.