let me correct myself you can get sufficient vitamin d from the sun but it does not necessarily ward off covid
https://www.medicalnewstoday.com/articles/326167#other-sources
grannny always took cod liver oil...might work for you
they have some that dont taste as bad as it did when i was a kid.
https://www.westonaprice.org/health-topics/cod-liver-oil/vitamin-d-in-cod-liver-oil/