Religion is a red-herring in this story, if a nurse has the option to refuse a vaccine it should be for any personal reason.
The question that I am the most interested in, is if the hospital has a similar policy for their doctors. If the vaccine is so obviously positive, then surely every doctor on staff would also have it. If every doctor has it and agrees that it is good, then I fully support mandatory vaccinations for nurses. I suspect however, that this is not the case, and that the mandate for vaccination is coming from somebody on the business management side of the hospital rather than somebody on the healthcare side of things.