I haven't had a single cold / bug so far this winter (will probably be struck down with something awful now!!) I have two children, work in a office, go to events with lots of people etc so I will have been exposed in the same way as anyone else.
Having good gut health helps your immunity, so if anyone has taken antibiotics recently, that will impact your gut health as it wipes out all your good bacteria as well as the bad and can leave you open to catching more bugs. I would have to VERY unwell to take anti-biotics these days. I think people are too quick to take anti-biotics and doctors can be too quick to prescribe them and people don't realise the harm they can do to your overall long term gut health.
I eat a diet high in fibre and plants, with lots of good fat. I do have treats and drink wine so I'm not militant about my diet, but most of what I eat is nutritious. My husband swears by fermented food and makes his own kafir which he has daily but I don't like yogurt so kafir is definitively not my thing - it stinks! I also take a pro-biotic capsule daily.
I also do a lot of exercise with 3-4 strength / weight training sessions a week. Sometimes less if I don't have time.
I think these things help me with a robust constitution and prevent me from getting as ill as others. If I feel like I might be about to come down with something, I usually seem to be able to shake it off after a day or two. I may just be lucky but think the above must help.
Hope everyone's illnesses bugger off and everyone is feeling better as we enter into the spring.