so vitamin d through the sun is not the same or what?

More vit D from more sun could be a side effect of better health. Sort of like if you found that using TikTok a lot was strongly correlated to very low covid-19 mortality; it would just be a marker for youth. This study makes it look much more likely that it's an actual effective intervention.

Vitamin D levels can be increased by either UV light exposure or dietary supplements. It's the same hormone in the end. However, bright sunlight exposure has other effects including changing levels of cortisol and nitric oxide. It's plausible that some of those other effects could also impact COVID-19 outcomes but we don't have any reliable data on that yet.

From what I’ve read it is the same, but most people don’t get enough due to modern lifestyle of working indoors and wearing clothes. If you’re working outside with your shirt off you’ll probably have good levels in the summer months at least, but sadly many of us are largely trapped inside with clothes on :-(

It would explain why there was a surge in positive rates in Arizona when summer hit. Everyone was inside where the AC was, not getting sun.

not op, but I don't think that's what's being implied. Just that there might be other benefits from spending time in the sun - so a study where the only variable is that one group got injections of vitamin D means that the difference is caused by the vitamin D not any of the other things that might be associated with high vitamin D levels (time in the sun, diet, etc).

The correlation observed for many things associated with vitamin D, is that healthy people spend more time outside than unhealthy people, not that being out in the sun is an inherently healthier activity. E.g. runners/athletes spend more time outside than those who are not, and the increased vitamin D exposure is mostly incidental. People with busier social lives tend to spend more time outside than those who do not. Etc.

Dr. Fauci says to take vitamin D if you're deficient to boost immune system

https://www.cnbc.com/2020/09/14/supplements-white-house-advi...

And a large proportion of people are deficient, probably most people actually. I’d rather he advised all people to get outside, do things outside under the sun and let your skin do its work, making all of the things it does, including D3.

For a lot of people who live in the Northern Hemisphere who are about to go into a period of long, dark nights during winter, your advice of "get outside, do things outside under the sun and let your skin do its work" is not really as helpful as taking vitamin D supplements.

Harvard Gazette 2017:

Study confirms vitamin D protects against colds and flu

https://news.harvard.edu/gazette/story/2017/02/study-confirm...