What do i do? nothing.
I haven't had a cold yet thanks to riding during winter i believe.
My half got a cold last winter and spread her germs everywhere contaminating everybody else in the family. Everybody was sick but me even though she coughed on me everyday.
I'm suspecting that riding during winter reinforced my immune system but i have no way to prove it. (To give you an idea I walked with the lightest tshirt i could find at -6C up to 1hr sometimes when most people i saw in the streets were with their heavy coats. So i believe my body got used to the winter because i was cold and sick like everybody else before)

Before that change, being sick usually didn't stop me anyway except when it was a matter of not contaminating other people.