I do not like what I hear about vaccination priorities in US. There is increasing emphasis on essential workers v. those who are in greater danger. There are even “racial equity” appeals..
As much as even medical workers are an appealing and deserving group, I think they are statistically less in danger (partly because they use protection properly) than old people, especially those in communal settings. It sounds that UK and Israel are doing it somewhat better – medical workers + age groups.
Halachik sources (R Feinstein, R Auerbach) seem to allow preferences for those who have higher chance to survide, and if not – first come, first serve and a lottery.
There is also an issue ledarchei shalom. If you start giving priority by vague rules, you will ensure fighting and people going around the rules. If rules are easily verifiable, like age, then it should be easier.