I think that your individual rights are not above the rights of the others not to be infected by you. We had years of expanding human rights while relaxing responsibilities, so much that people act like selfish babies whenever they are (rightly or wrongly) frustrated against the state.The big question is if this pandemic is so severe that forcing vaccines on people who don't want it, is considered necessary to save lives.
...other good questions...
The implicit vaccine mandate would have been an authoritarian overreach if it was taken outside of epidemic that devastates the economy and sometimes kills or maims people. It would be also okay against any other highly infectious or deadly (or both) disease. So either infectiousness or deadliness is a good criterion for making stuff obligatory.
Explicit vaccine mandates for government workers is also another measure coming up and it's been applied in several states by now. This is even more problematic constitutionally.
Whether regular flu vaccines could be mandated by the same logic, I'm not sure. Seasonal flus are much less infectious (and therefore not likely to turn into epidemics), although sometimes they can be quite deadly during some winters (but you know this stuff much better).
That sounds problematic until you try to give an example. Mandatory influenza shots every winter? Washing your butthole when entering government offices, so they won't be grossed out when screwing you over??It opens a door for governments to force prophylactic measures on the population as long as it can be argued it saves lives.