This supports the idea that Vitamin D helping with COVID is probably causal rather than just a correlation.
[1] https://www.sciencedirect.com/science/article/pii/S096007602...
[2] https://chrismasterjohnphd.com/covid-19/finally-confirmed-vi...
I went in skeptical even though intuitively being deficient in vitamin d makes sense, this isn’t convincing but I agree with with their conclusion that it’s worth a bigger study.
If someone reading is wondering whether to maintain a healthy level of vitamin D to help if you get covid, yes you should. Should have done that before this study ofc.