[xav0989]

Why would we need to include an exemption for natural immunity?

Doing so would add additional work to the _already overworked_ health agencies, labs, etc. You'd need to test people to ensure that they have an adequate immune response (at least on par with what the vaccines provides). With unlimited resources and total information, then sure, doing either vaccines or natural immunity would work, assuming that the natural immunity is at least on par with the vaccines. However, given that we don't have unlimited resources nor total information, it's much simpler for the health agencies to ask for everyone that doesn't have a medical exemption to get vaccinated.