Up front: this is NOT a magic bullet, but a recent study says decreased levels of Glutathione may have something to do with the problems found in COVID19 patients that had a hard time. First link here is the study (written in technical lingo) and the second is ten ways to increase Glutathione naturally. There are supplements available for purchase, but most of us would rather go the ‘natural’ route where possible.

First link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7263077/

and second link: https://www.healthline.com/nutrition/how-to-increase-glutathione

Again, NOT a magic bullet, and after reading the second link, their recommendation is basically to eat a wide variety of healthy foods and live a healthy lifestyle. This won't prevent you from getting COVID19, but it might make it a bit easier to get through IF this study turns out to be correct.