good thing we never really have winters here anyway

as a long term germaphobe and person with high risk of infection for the better part of the past two decades, the most important thing in avoiding getting ill from others is constant vigilance - assume everything you touch is contaminated and act accordingly

if you use your elbow to open a door, then your elbow is now contaminated, if you touch your elbow on your desk, then that's now contaminated

it's actually a pretty awful way to think and very difficult to keep up over the long term

but really you just need to apply the basics of hazard management to this:
eliminate the hazard - stay at home
substitute the hazard - use what you have at home
isolate the hazard - avoid contact with anyone and anything
engineer to control the hazard - screens at check outs
administrative controls - stay 2 metres apart
PPE - last resort when you can't do the others

which is why we need to retain PPE for those who need it most