Glasses might be protective too. So (less seriously) is eating garlic.
One early statistic observation was a French observation that smokers are better than surviving Covid. This research did not age well. Presumably, observation can be explained as following: younger, generally healthier in general, smokers get hospitalized, and are more likely to survive.
Even latest Israeli research in Lancet – 99% reduction in difficult cases, 85% reduction after first dose. This is among health-care workers, not elderly.