[Old-timey sounding illness] used to be quite common, infecting [a large majority] of children before they were [too young to up and die]. Since the advent of the vaccine, that number has dropped by [probably over 90 percent, because vaccines are generally dope], which makes it easy for people to forget what it was like to get debilitating illnesses on the regular as a child. That's the beauty of modern medicine. And yet we still see periodic outbreaks, because not everyone gets vaccinated. A very small percentage of people have immunocompromising diseases that preclude them from getting shots, but a troubling number of parents are avoiding vaccines for other reasons. Some believe it's not healthy to give kids many shots all at once (it's actually fine, according to many studies), others still cling to "research" that claimed a link between vaccines and autism, which has long-since been proven fraudulent.