Whilst it's true that germs are all around us once on board a typical airliner, unless you are immunosuppressed all the normal characters will have minimal, if no effect on you. Hand washing after touching high traffic areas and/or toilets goes without saying to alleviate possible nasty infections. The elephant in the cabin is that which we breath, the filters aren't changed/cleaned often enough for the removal of some really nasty virus' and not to forget the toxic fumes that have sometimes made their way into the interior from the engines due to faulty MX….Perhaps we should wear masks, now that's guaranteed to get you strange looks
SHJ