So when the vaccine comes out, who should governments mandate vaccinations for...all age groups, or only those at high-risk?
If this were 1963, the government would order everyone to get it, and everyone would line up and be vaccinated. That is what happened when the oral polio vaccine was developed. That would be the best thing to do. That saved thousands of lives. Unfortunately in the present era people no longer follow the rules and do what experts say they should do. People have ridiculous ideas about what constitutes "freedom." They do not trust science or experts. I blame the Vietnam war and right-wing radio for that. Regardless of what brought it about, you can no longer order people to be vaccinated. So, we will have to let people do as they please. I expect that enough people will get it to ensure herd immunity. If I were the Emperor of America I would be tempted to make a rule:
You don't have to get the COVID-19 vaccination. But if you don't get it, and you get sick, you are on your own. You will have to pay 100% of hospital costs. No insurance, and no government help of any kind will be given to you.
To put it another way, the people who die from the disease after a vaccine is made available should be given a Group Darwin Award for improving the overall intelligence of the population.
Vaccinations for children is a different matter. An adult has a de facto right to kill himself. He can drink himself to death. He can refuse medical treatment that could easily cure him. But a parent should not be free to endanger a child by refusing to have the child vaccinated against common childhood diseases. That was not allowed in the past. It is no longer allowed in California, Mississippi or West Virginia. It should not be allowed anywhere. The child's life, health and welfare trumps the adult's lunatic conspiracy theory beliefs. For the same reason parents are not allowed to cut off their children's hands.
Having said that . . . it might be prudent to withhold a COVID-19 vaccine from children at first. I would wait until it has been administered to millions of adults and we are certain it is safe. Children seldom die from COVID-19 so we should not risk vaccinating them at first. Old people (including me) should get it first because if it knocks us off, so what? We are old and will die soon anyway. Compared to children we should be considered expendable and well suited to be guinea pigs.