It has nothing to do with authority though it has everything to do with speciality. Doctors are the only ones that know better (duh) it's the nature of their profession. When you need to send a rocket in orbit you will go to a rocket scientist when you deal with a virus you will go to an epidemiologist. The projection of the deaths spread et cetra will go from data that the medical society gathers to mathematicians to build up a relatively simple model and get some rough numbers out of it to get a better picture of the threat. If the threat is big enough expect radical changes to your life style if you consider your self smart enough to trust those that are in position to do those models if you think you are smarter you can try out your luck and your own model, if you don't believe any of that you are always free to go out in a hospital and volunteer to help out and you will be able to get some data and do some empirical science for yourself. I don't think anyone will stop you to volunteer at hospital at this point. They are going to need more personnel anyway, I say it is safe to assume the threat is real but its not deadly if you don't have preexisting conditions. Limiting the spread is not going to stop the virus. Because of course it can't stop a virus from spreading we know that it is going just give a more reasonable window to the hospitals and the medical personnel to handle the situation avoiding the conjunction. There is simple not enough doctors and equipement to hospitalise everyone infected at the same time. But don't worry everyone or at least the vast majority of human population eventually "will" get it, there is no stopping that only slowing it down.