Require the pet be licensed and vaccinated. 

Similar, they are required to have vaccinations, etc.   

In the case of a SA or ESA, you as the landlord has the right to verify the SA or ESA, by request to see documentation and call to verify with the provider to make sure the certification is legit, valid, active and current, and wellness documentation that the animal is in good health, free of parasite, flea, ticks, vaccinated etc...

If a vaccine gets approved, the discounts offered might be disappearing in a heartbeat as sellers know that the economy and the market will recover (further).

In addition, we require that all pets be spayed/neutered and they must provide proof of rabies vaccination and local municipality pet licensing. 

This is not going to be over with for at least another year, and even after that some people are afraid to take a vaccine.

(The hope is that by 2021, that remedies for this virus, will have been created; however, creating viable vaccines can be a long process, given that many vaccines are defective, due to they create what is called disease enhancement, that is that they also have the undesirable effect, of making a virus worse, while designed to precipitate human immune response to a virus.

Have a list of 4 people for this apartment.This is what happens when you can't evict for 2 years, pay people NOT to work, fire people for not taking a vaccine that is proving to be less and less effective and throw stimulus checks out of a helicopter for 2 years to people who didn't need it to start. 

In Pittsburgh they developed the polio vaccine, heart transplants and 7 organ transplants;  they didn't do that at the Bessemer furnace.I've said it countless times on Bigger Pockets and other places that "Tax Sales are the most hazardous method of buying real estate." 

Fauci says the vaccine is safe.