You've made a an assumption about nurses and health care workers, when I'm sure that you do not know what sort of diet or health status nurses or health care workers have.
The issues you raise about mandatory vaccination are valid though IMO. I personally don't agree with mandatory or forced vaccinations, I think it should be an individual choice, but unfortunately, that is not how the corporate world works. I guess in your country, people who had an aversion to being vaccinated, would need to work in different areas, if they didn't want to comply with the wishes of the corporation they work for.
Health workers in my country are not required to be vaccinated, it is left to the individual to decide. We also have a national health system, which is paid for by our taxes, and vaccinations are free under this system, to those who choose to be vaccinated.
If I was someone that was working with sick people on a daily basis, I would choose to be vaccinated against communicable diseases, to protect myself and my family. I couldn't think of anything worse than being responsible for the unnecessary suffering of my family members or other people, simply because I chose to be vaccinated.