Vitamin D: "Several recent studies have looked at the impact of vitamin D on COVID-19. One study of 489 people found that those who had a vitamin D deficiency were more likely to test positive for the virus that causes COVID-19 than people who had normal levels of vitamin D. Other research has observed high rates of vitamin D deficiency in people with COVID-19 who experienced acute respiratory failure. These people had a significantly higher risk of dying. And a small, randomized study found that of 50 people hospitalized with COVID-19 who were given a high dose of a type of vitamin D (calcifediol), only one needed treatment in the intensive care unit. In contrast, among the 26 people with COVID-19 who weren't given calcifediol, 13 needed to be treated in the intensive care unit." https://www.mayoclinic.org/diseases-conditions/coronavirus/expert-answers/coronavirus-and-vitamin-d/faq-20493088 Note that the current RDA(Recommended Daily Allowance) is for bone health. For optimal health, it may be more. From Liz: "Sunshine and fresh air will not keep you safe." Partially correct. They can increase your health and improve your body's covid response. Sunshine helps your body produce Vitamin D. Time outside for me generally equals exercise - in the garden, doing construction, walking/hiking and more. For the past year and a half, my one gig as a sound person was outside, providing audio for the local state university's graduation in May, with everybody masked and spaced 6'.