It’s always advisable to avoid travel if you’re sick. But no stay home directive is sustainable for long periods, and urgent life events will overlap with this outbreak. So, guidance about this will be targeted, and ideally informed by easy screening and testing that can advise people with the sniffles whether they are fine to get on a plane or should urgently self-quarantine.
See the U.S. State Department STEP guidelines for individual countries you might be traveling to; and the CDC guidelines. The New York Times also has a daily report, issued in the evening, about the status of the virus.
Disinfecting common surfaces while traveling; carry Handi-Wipes or something similar to wipe down everything near you in the plane – seat buckle, arms, tables, vents, switches, walls, if you have a window seat. Everything. And do this before you settle in. (I have done this for years on every flight I’m on, and people have looked at me as if I’m crazy. I think not anymore.) And don’t put your hands in the seat pocket unless you sanitize immediately afterward.
Whenever you travel, carry Rx meds with you (don’t put in a checked bag) and, if you can, always have extras, just in case you are delayed. Also, carry a list of the meds you need and use generic/chemical names, so that you can fill them in foreign pharmacies if need be.