This is medicine. You have to demonstrate that a treatment is safe and effective before you can begin using it. You even have to show that it is likely safe and

This is medicine. You have to demonstrate that a treatment is safe and effective before you can begin using it. You even have to show that it is likely safe and effective before you even get to test on humans. The only difference with vaccines is that we have already demonstrated that they are safe and effective, and what they prevent is unusually damaging to society (epidemics). They are also unusual in the sense that not getting vaccinated yourself increase the risk of others, even if they have been vaccinated.