[abakker]

Chicken pox may be harmless as a child. That virus also causes shingles and that is NOT harmless as an adult.

edit to add: things like HPV seem harmless, but HPV infection is linked to the vast majority of cervical cancer. Things like epstein-barr are implicated in certain cancers as well.

There are no "good viruses" and just because they have mild initial symptoms does not make them harmless.