[mlyle]

IV calcifediol (Vitamin D) in early-stage COVID has improved outcomes in small randomized controlled trials.

Oral vitamin D has been shown to be ineffective at this point, but this isn't surprising: it takes a long time of sustained oral supplementation to raise levels.

Then there's a whole lot of evidence showing correlation, but as you point out, low vitamin D is an indicator of frailty. This is much weaker evidence.

I think it's likely that taking oral vitamin D before infection probably improves outcomes somewhat.

[travmatt]

I haven’t heard vitamin d administration is associated with better outcomes, but I’ve heard that vitamin d levels are inversely correlated with outcomes - i.e., people should take a blood test and determine if they are vitamin d deficient, and supplement as needed.

[mlyle]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456194/

> Of 50 patients treated with calcifediol, one required admission to the ICU (2%), while of 26 untreated patients, 13 required admission (50 %) p value X2 Fischer test p < 0.001.

Strengths: Randomized, very strong effect, strongly statistically significant.

Weaknesses: single trial, single center, relatively small sample, not blinded.

https://pmj.bmj.com/content/early/2020/11/12/postgradmedj-20...

> Greater proportion of vitamin D-deficient individuals with SARS-CoV-2 infection turned SARS-CoV-2 RNA negative with a significant decrease in fibrinogen on high-dose cholecalciferol supplementation.

Strengths: Randomized, blinded trial

Weaknesses: single trial, single center, relatively small sample, secondary outcome measure