Can someone explain to me how doctors see so many patients and they don't get sick even if they see patients with fever, etc.. do they take injections?

Good question: I think that it is because the profession occupies the mind apart from simply "making money". Happiness at work is of inestimable importance and few in this robot culture are able to achieve it. If the mind is healthy, so will the body be because we are nothing without the brain. Also, perhaps doctors know all too well how important is diet, the fuel that enables all our functions.