Vitamin D-let common sense prevail-on the balance of probabilities.

High latitude, dark skin type, overweight, inflammatory conditions, are all predisposing factors for severe vitamin D deficiency (serum 25(OH)D below 25 nmol/l) [1]. The authors of the latest rapid evidence review for vitamin D and Covid-19 [2] find the evidence not compelling enough to advise population-wide prophylactic vitamin D supplementation to prevent Covid-19 severity. They confirm, however, vitamin D’s role in immune modulatory processes. Should not therefore at least those risk groups deserve to be advised on adequate vitamin D supplementation, better even, have their serum 25(OH)D assessed?

I disagree with the authors that existing national guidance in the UK on vitamin D supplementation appears appropriate. Firstly, this guidance is not well taken up [3], secondly, it does not abolish vitamin D deficiency, it just reduces it by a small degree [4], and thirdly, it completely ignores nutritional science by advising the same dose for all (400 IU), whether for a baby or an overweight adult.

The risk groups for vitamin D deficiency and severe Covid-19 disease are overlapping. Evidence for the benefits of avoiding D-deficiency during this pandemic far outweighs the theoretical risk of overdose. Physicians and chief medical officers should urgently and pro-actively seek to abolish vitamin D deficiency, now, ahead of a third wave, rather than only wait for further trial results.