Animal infections of SARS-COV2 are quite rare. People aren't giving it to their cat who gives it to the neighbor's cat who gives it to the neighbor. It's not killed off by vaccines or natural immunity because the it mutates too much. It's an RNA virus, and RNA replicates poorly. People can get COVID multiple times and can get it after being vaccinated as we all know.
Animal reservoirs can exist for RNA viruses, DNA viruses, or any other parasite (e.g. the plasmodium that causes malaria). Animal reservoirs are most often found in the tropics which is why they refer to the diseases as tropical. But they are not tropical, anything but. They are third world diseases and third world countries are most often in the tropics.
This Dr. Dan Stock thinks it’s the animal reservoir that makes COVID impossible to stop:
https://www.youtube.com/watch?v=jtvQ47fohqc
Tell me what you think after watching.