I honestly can't believe I'm having this conversation in an airline forum. I would hope most people in the airline industry would understand the need for proper training and certification. This suggestion is the equivalent of someone saying couldn't a 737 pilot just jump in the cockpit of a A350 and fly it without a type rating!
My suggestion is not like saying a 737 pilot could jump into a a350 and fly it without a type. Its more like saying why cant a person who already has training, not be given a specific course to just administer vaccines.
Doctors, nurses, firemen, paramedics all have better things to be doing than jabbing the entire population. Having a team of maybe 20 trained people overseen by a fully trained doctor to supervise and run a centre would be a better use of resources.