This is a health warning about Vitamin Davis, and COVID-19, and pre-prints, and vitamin D.

First published in February 2021.

David Davis

This is a very important study on vitamin D and Covid-19. Its findings are incredibly clear. An 80% reduction in need for ICU and a 60% reduction in deaths, simply by giving a very cheap and very safe therapy - calcifediol, or activated vitamin D.  

What does this study actually show?

Well, as many have pointed out, it is neither “large” or “well-conducted”, and in fact quite flawed, randomising entire wards and not individual patients. This makes it nearly unreadable in its current form.

Here is a great Twitter thread on why:

F. Perry Wilson, MD MSCE

Folks, we need to talk about this Vitamin D trial. I have no stake in this game - take Vitamin D if you want but this pre-print is super sus. (THREAD)  

So, how did it get published if it was so flawed?

Well, the answer is, it DIDN’T.

This is a “preprint”, which is like a DRAFT before the study has been looked at by other scientists and checked for mistakes.

Preprints warning. | The Lancet

I would be very surprised if this gets published in its current form at all.

“Preprints” have pros and cons. On the plus side they are fast to get out into the world and universally accessible, but on the downside they are fast to get out into the world and universally accessible.

“Preprints” have informed debate in key scientific areas rapidly (like new variants in COVID), but at the same time fuelled misleading headlines and health beliefs. That is why “peer review” is so essential.

Does this study tell us much about COVID-19 and vitamin D? Not really.

Not yet anyway.

Should we give vitamin D into the veins of unwell COVID patients? Not without better evidence of benefit.

There is a summary of the evidence here. Top takeaways:

  • No evidence for COVID/vitamin D;
  • Vitamin D deficiency is found in groups at risk of COVID, but could be from common causes of both (e.g poverty);
  • Vitamin D normally goes DOWN when you are sick anyway.

Should I take vitamin D, then? Yes, as the government recommends it every winter. (For full disclosure, I take it. But just in general. Not for COVID-19)

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So, what is David Davis up to?

Well, miracle COVID cures are very popular during the pandemic: hydroxychloroquine, ivermectin, zinc, vitamin C... But most of these haven’t seen any real-life benefit in actual “well conducted” trials.

These “simple” cures play into the narrative that the “scientists have got it wrong”, which is in one part hope, one part frustration and one part conspiracy theory. And it is this narrative that is very erosive to public health policy.

The irony is that many COVID clinical trials have been run on all sorts of known medicines, at rapid pace, to try and answer these questions systematically. That is where the evidence for steroids came from, for example.

It appears that David Davis may have been briefed by one of several individuals downplaying COVID-19 severity and lockdowns. Which is all predicated on being able to “live with COVID”, and go back to normality.

Funnily enough relatively normal lives are being lived already globally with No COVID, in Australia, New Zealand, Singapore. Yet no country has managed to “live with it”.

And this is the issue with Vitamin Davis: it contains false hope, flawed evidence, and may contain other ingredients hazardous to public health.


So in summary:

  1. DO take vitamin D if you are recommended it;
  2. We don’t know if vitamin D is helpful for COVID;
  3. Avoid Vitamin Davis. 

Update, 19 Feb 2021: The preprint has been removed from the Lancet and replaced by the following message:

Going Further:

Dr Dominic Pimenta, Doctor. Writer. Researcher. Chairman of Active NHS campaigner.


Check their Voting Record:

🗳️ David Davis

[This piece was first published as a Twitter thread and turned into the above article on 19 February 2021 with the purpose of reaching a larger audience. It has been minorly edited and corrected, and published with the author’s consent. | The author of the tweets writes in a personal capacity.]

(Cover: Flickr/Estonian Foreign Ministry. - David Davis MP. | 23 November 2017. / Licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.)

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