Most of them refuse because it's still NOT signed off by the FDA.. Trump would have had that done 2 or 4 months ago... Like he did setting a fire under the lazy asses on the vaccine...
The vaccines were already in the works while Trump was busy spreading disinformation about the virus till the very day he left office. He didn't do shit. J&J was the only company that even took federal dollars. Moderna and Pfizer moved forward without it and came out with a vaccine first.
These nurses aren't holding out till FDA approval. The FDA will most assuredly approve the vaccines. It's the whole process which takes a while. This is about the right wing turning anything related to covid into a culture war. This is why a 24 year old nurse went to her grave refusing to believe in the vaccine, till the very end. They've given up all independent thought and have given it all to the cult.