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The prevalence of SARS-CoV-2 infection was 12.5%, 8.1%, and 5.9% for patients with deficient, adequate, and high levels of serum Vitamin D, respectively. This s

The prevalence of SARS-CoV-2 infection was 12.5%, 8.1%, and 5.9% for patients with deficient, adequate, and high levels of serum Vitamin D, respectively. This study clearly demonstrates correlation but further studies are needed to establish causative links. The data comes from Quest labs that allowed the researchers to use the unique patient ID to associate SARS-CoV-2 PCR lab results with 25(OH)D blood test results. The dataset includes 190K patients.

beagle3 6y ago
Should be noted that the vitamin D levels were from the past 12 months. This is pure correlation, as Deva Boone’s excellent blog clearly explains. However, a few days ago there was on the HN front page a link to what appears to be causal effect - Covid patients who were given vitamin D On admission did better than those who didn’t. That study had some limit and they had a couple of uneliminated confounders - but the body of evidence does hint that proper vitamin D supplementation is likely beneficial in fighting Covid.
- janekm 6y ago
  I believe this is the study you are referring too: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456194/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456194/ Massive effect size which somewhat compensates for the small N in this seemingly well-designed study.
fiatjaf 6y ago
No study can ever establish causative links.
- rflrob 6y ago
  A properly designed, well powered, double blind randomized controlled trial does a much better job at establishing causation than a retrospective correlation study, though.
- IgorPartola 6y ago
  Really? So atomic bombs explode when we set them off just by coincidence? Penicillin just happens to be administered every time the body decides to start fighting a bacterial infection?
  - raverbashing 6y ago
    According to some "scientists", if you sailed looking for India and found the Americas your experiment failed and you should go back and now search for the Americas.
- ak217 6y ago
  Maybe you meant "no observational study"?
- samatman 6y ago
  "The effects of high-dose cyanide on mortality in lab mice" will establish a very strong correlation, with an impressive effect size. I suppose inferring causality still requires a leap of faith...
  - Gibbon1 6y ago
    More recently I've seen more discussion of observational power. That's related to bayesian probability. If someone said they fed a 3 month old mouse a 0.1 mg dose of Chemical X and it died immediately. Hard to argue that sample size of 1 means the result is worthless anecdote. The observability is pretty good.
- jacquesm 6y ago
  That's utter nonsense. Of course they can. And they often do. Studies have limitations usually based on the statistics as a result of the size of the group and the degree to which confounding factors can be ruled out. But it is perfectly possible to establish a causative link by doing a well designed study, possibly even with small sample size.

beagle3 6y ago

Should be noted that the vitamin D levels were from the past 12 months. This is pure correlation, as Deva Boone’s excellent blog clearly explains. However, a few days ago there was on the HN front page a link to what appears to be causal effect - Covid patients who were given vitamin D On admission did better than those who didn’t. That study had some limit and they had a couple of uneliminated confounders - but the body of evidence does hint that proper vitamin D supplementation is likely beneficial in fighting Covid.

janekm 6y ago
I believe this is the study you are referring too: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456194/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456194/ Massive effect size which somewhat compensates for the small N in this seemingly well-designed study.

fiatjaf 6y ago

No study can ever establish causative links.

rflrob 6y ago
A properly designed, well powered, double blind randomized controlled trial does a much better job at establishing causation than a retrospective correlation study, though.
IgorPartola 6y ago
Really? So atomic bombs explode when we set them off just by coincidence? Penicillin just happens to be administered every time the body decides to start fighting a bacterial infection?
- raverbashing 6y ago
  According to some "scientists", if you sailed looking for India and found the Americas your experiment failed and you should go back and now search for the Americas.
ak217 6y ago
Maybe you meant "no observational study"?
samatman 6y ago
"The effects of high-dose cyanide on mortality in lab mice" will establish a very strong correlation, with an impressive effect size. I suppose inferring causality still requires a leap of faith...
- Gibbon1 6y ago
  More recently I've seen more discussion of observational power. That's related to bayesian probability. If someone said they fed a 3 month old mouse a 0.1 mg dose of Chemical X and it died immediately. Hard to argue that sample size of 1 means the result is worthless anecdote. The observability is pretty good.
jacquesm 6y ago
That's utter nonsense. Of course they can. And they often do. Studies have limitations usually based on the statistics as a result of the size of the group and the degree to which confounding factors can be ruled out. But it is perfectly possible to establish a causative link by doing a well designed study, possibly even with small sample size.