Stay at home?

Use Clorox wipes to wipe down everything in the immediate
vicinity of your seat.

Avoid touching anything that is not in the immediate vicinity
of your seat and then touching yourself.

And then there are the airborne germs one may breathe
after the sick person has sneezed, coughed, etc. These can
travel a long distance so you are not safe even separated by
a seat or two.

You might cut your risk by wearing a mask but there is some
debate on that.

If you decide to wear the mask you need to decide when to
start wearing it... on the taxi ride to the airport? ...inside the
terminal? ...inside the plane? Fact is, you are at risk of catching
something the minute you step outside your home assuming of
course you are not already sick or are in contact with someone
sick.