Oscillococcinum works for a lot of people but not for me. I have a whole box of homeopathic remedies, which usually work for me if I take the right one.
I take 1000 mg of C every day of my life, rarely get a cold. I added 50 mg zinc recently, because my thumb nails were getting weird striations, which indicate low zinc in the body. Apparently zinc adds another layer of protection from colds.
Three years ago, I had a cold and it went straight to my chest. Took Mucinex and Chlor-trimeton. My good friend who had recently retired as a pharmacist brought a whole box of stuff over...more exotic remedies...but decided I was doing fine with the simple things I was taking. Lasted three weeks. Hasn’t come back.
I think the person who mentioned D3 is probably on the right track, too. We just don’t get as much Sun as we evolved to require and got in the past.