This may sound strange and counterintuitive, but open your windows up!!!
My ID doctor told me this. The reason is this.
What do we do in the summer? We have our windows open, and we are outside a lot more.
What do we do in the winter? Just the opposite.
How many sick people do you see in the summer?
How many sick people do we see in the winter?
The reason we get sick in the winter is not that other people are sick (but it is a contributing factor), but we are holed up in our houses. With the furnace running, it keeps recirculating the same air over and over and over. After awhile breathing all that stale air makes us sick. By opening a window in each room for only 5 minutes every other day, it lets fresh air in. Then your furnace is not recirculating nasty old air, but fresh air. Just think, your coughing and sneezing, and all those germs recirculate back through your heating ducts, making you sicker.
SO OPEN YOUR WINDOWS!!!

Our ID doctor is a big believer in chicken noodle soup so I make that for hubs pretty regularly, even as a preventative measure. I'm follow a keto diet so no noodles for me.
I am going to start opening windows for a 20 minutes or so to air things out, that is a good idea. But here in rainy and cold Pacific Northwest, we can't keep them open too long.
I got my flu shot but hubs can't get his yet because he is currently on steroids but hopefully those will end soon and he can get the shot.

Hmmmm. Never thought about actively avo avoiding them but more on staying as healthy and active as i can

The only threat is from direct contact with someone infected with a bug or flu. I've had HIV and full blown AIDS but I've survived with the simplest of rules. WASH YOUR HANDS every chance you get when out in public environments.

I love in the mountains near los Angeles, its cold, I mean its winter here, we are at 6900 feet elevation, so the answer to that would be, I shut my Windows all winter long, even though we are in southern California, we are a winter town, and ski village. If we get sick, we get sick, but we have both had our flu shots as well.