Vitamin D reduces the odds for severe COVID-19 by a factor of around 5.
(49% probability)Question
Does Vitamin D reduce the severity of COVID-19 outcomes?
19 Oct, 2020Answer
Background
There is a heated debate regarding the effectiveness of vitamin D in improving COVID-19 outcomes. While numerous studies show a correlation, many claim it is due to confounding factors. A few controlled trials showed a strong effect, but the most notable one, conducted in Córdoba, Spain, had significant flaws that prevented it from being widely accepted.
More studies are underway, and within a year or so we will likely get a more certain answer, but a probabilistic analysis of currently available information can reach a useful conclusion faster, potentially saving hundreds of thousands of lives.
Additionally, the conclusion below is included in the Rootclaim $100,000 challenge.
Note: this is a simplified analysis; the full version was published in September 2020 on the Rootclaim blog.
Hypotheses Considered
Calculated Results
Calculated Results
1
49%
Vitamin D reduces the odds for severe COVID-19 by a factor of around 5.
49%
2
29%
Vitamin D reduces the odds for severe COVID-19 by a factor of around 20.
29%
3
15%
Vitamin D has no effect on COVID-19 outcomes.
15%
4
5%
Vitamin D reduces the odds for severe COVID-19 by a factor of around 2.
5%
5
2.2%
Vitamin D worsens COVID-19 outcomes.
2.2%
Starting Point
Initial Probabilities
Name
Initial Likelihoods
Damage
10%
No Effect
67%
2-fold
15%
5-fold
5%
20-fold
3%
As a baseline, few drugs are effective for any specific disease. However, there are multiple studies showing a correlation between vitamin D and COVID-19, and several proposed mechanisms of actions. On the flip side, there is the risk that vitamin D could actually exacerbate COVID-19 by increasing the expression of ACE2.
We will represent these facts with the following prior probabilities of using a high-dosage, short term, vitamin D treatment for Covid 19:
-
Damage – 10%
-
Nothing – 67%
-
2-fold improvement – 15%
-
5-fold improvement – 5%
-
20-fold improvement – 3%
Name
Initial Likelihoods
Damage
10%
No Effect
67%
2-fold
15%
5-fold
5%
20-fold
3%
Evidence
Effect
Reduced admittance to ICU
Name
Effect
Updated Likelihoods
A randomized controlled study of 76 patients found significant improvements in patients treated with vitamin D relative to patients not treated with vitamin D. Specifically, 13 of 26 patients in the control group were admitted to the ICU, while only 1 of the 50 patients treated with vitamin D were admitted to the ICU.
Name
Effect
Updated Likelihoods
Discussion