Got this from Southwest Airlines...they are worried:
Aircraft Cleaning: We spend between 6-7 hours cleaning each aircraft every night, and, as of March 4, 2020, we have enhanced our overnight cleaning procedures. Typically, we use an EPA approved, hospital-grade disinfectant in the lavatories and an interior cleaner in the cabin. Now, we are expanding the use of the hospital-grade disinfectant throughout the aircraft, and it will be used in the cabin, on elements in the flight deck, and in the lavatory. This goes beyond the standard CDC guidelines.
Also, we equip each of our aircraft with a HEPA (High Efficiency Particulate Air) filter, which filters out recirculated air onboard each plane to remove airborne particles. HEPA filters are also used in hospitals to provide patients with clean air.