As elevator technical experts we would not presume to offer advice on pandemic medical issues, even regarding elevators. Information from various health authorities is available and it is fluid.
It seems clear that limiting the number of people in an elevator is advisable, as is the wearing of masks within the elevator. Frequent cleaning of surfaces is a good idea but note that it is very easy to damage the electronic fixtures. Below is some of the best advice we have seen on the subject, this is courtesy of Liberty Elevator.

Avoid using alcohol based cleaners directly on elevator buttons, as they may damage the lacquered surfaces and cause some plastic components to become brittle over time.
For non-lacquered fixtures, you should use alcohol at the lowest concentration that will disinfect. For most elevator surfaces 70% alcohol solution is recommended.
Using none abrasive, spray on cleaners with a disposable paper towel or microfiber cloth is recommended when wiping down your elevator.
Spray cleaners should be applied to a clean rag or paper towel, then used to wipe down elevator buttons. Never spray cleaner directly on components.
Sponges should be avoided as they may harbor bacteria and the excessive moisture may damage your elevator’s electronic components.
We do not recommend bleach based solutions as they will react negatively with Polycarbonate fixtures.
In general, for Non-Bleach disinfectants (ie: Lysol Wipes) we don’t have enough information about the specific chemicals that are the active disinfecting ingredients, so we would recommend abstaining from use.