Hi!
I am a lawyer. Which country do you live in? Every country has a different constitution. Here in Hungary, the constitution says: "It is forbidden to conduct medical or scientific experiments on human beings without their informed and voluntary consent." According to the Hungarian constitution, this cannot be suspended or restricted, even in a special legal order. (For example, it cannot be restricted in an epidemic emergency.)
The other thing. If your country has ratified an international human rights convention, it is bound by it. For example, the International Covenant on Civil and Political Rights says: "In particular, no one shall be subjected without his free consent to medical or scientific experimentation."
These things may be against the criminal law of your country. For example, in Hungarian criminal law it is a crime to violate the rules of research on human subjects; to interfere with the human genome; to abuse poisons; to commit quackery.
Portugal here, and though our constitution says the same, there's also an article that says the government can take the rights off citizens in cases of great emergencies, such as a pandemic. And indeed they have done that. Enforcing confinement, creating stupid and ridiculous laws. And fucking up the economy. This opens doors for mandatory vaccination. It's not impossible.
From what I understand, any rights such as free moving around and informed consent on vaccination, can be thrown out of the window with the rest of the rights that they have taken from us, because public health is more important than human rights. (according to them). I will resist for as long as I can, and I'm looking for a valid excuse not to take it. But I don't have allergies or anything like that. Not sure what to do here if they start enforcing it, but I want to prepare