Small Pox, Polio, Diphtheria, Pertussis, Mumps, Measles, Rubella, Shingles.
Still some bad ailments for which there is no vaccine but we no longer worry much about them because there is a treatment. TB, Anthrax, Plague to name a few.
I see three ways to lessen this COVID-19 deal. Vaccine which seems to be a ways off, pursuing herd immunity which will exact a huge toll of premature deaths or long lasting infirmities, or an effective treatment for those who come down with it.