Unfortunately, there's always a group that doesn't exercise common sense and doesn't care, so that they never get around to taking public health precautions on their own.
And these days, we also have the folks who are convinced that every vaccine is a health threat and that all vaccination programs are a conspiracy. Their spiritual ancestors were convinced that Jenner's inoculations would cause them to break out in cows.
If everybody were as sensible as you and I on such matters, it wouldn't be a problem. And if the folks who refuse to take precautions infected only themselves, it still wouldn't be a problem. But they infect other people -- including those who do get vaccinated (although generally the disease will be milder). That's why herd immunity is important.
And mandatory vaccination goes back to 1807. I'm not a big fan of government intervention, but preventing epidemics is a traditional, core governmental function along with keeping the peace and regulating trade. There's a lot of other government interference that needs to go before we interfere with public health mandates.
>>But they infect other people -- including those who do get vaccinated<<
The principle objective of a vaccine is to “immunize”. If those who get the vaccine are immunized against the affects of a disease then only those who do not get the vaccine are affected and suffer the consequences. Your assertion that you or the government need to force the “collective good” on people less “sensible then you or I” is rather condescending and rather scary. That attitude in the past has led to some rather evil results. Personal responsibility demands that we allow people to fail or succeed. Allowing people to avoid personal responsibility is unkind and leads to the development of an attitude of dependence that demeans that individuals self worth.
>>preventing epidemics is a traditional, core governmental function<<
Would you please direct me to the part of the constitution or amendments that address your support for the “core governmental function” to force people to be vaccinated?