Doctors, maybe, but it was the scientists who told them about the germ theory of disease, for instance.
I've read, but not confirmed for myself, that in the US the biggest gains in health came in the post-Civil War period, when "plumbers and janitors" made the difference. Of course, that's really starting with, after the science, the civil engineers who designed the public works systems that supplied clean water and took away sewage, and let's not forget that politicians and like who found it worthwhile to buy votes that way (now, they take our infrastructure for granted and buy votes more directly...).
