VERDICT
We found no clinical evidence on vitamin D in COVID-19. There was no evidence related to vitamin D deficiency predisposing to COVID-19, nor were there studies of supplementation for preventing or treating COVID-19.
There is some evidence that daily vitamin D3 supplementation over weeks to months may prevent other acute respiratory infections, particularly in people with low or very low vitamin D status. This evidence has limitations, including heterogeneity in study populations, interventions, and definitions of respiratory infections that include upper and lower respiratory tract involvement.
The current advice is that the whole population of the UK should take vitamin D supplements to prevent vitamin D deficiency. This advice applies irrespective of any possible link with respiratory infection.
Clinicians should treat patients with vitamin D deficiency irrespective of any link with respiratory infection.
Policymakers should attend to public health measures to ensure the population has adequate vitamin D intake.
Joseph Lee, Oliver van Hecke, Nia Roberts
On behalf of the Oxford COVID-19 Evidence Service Team
Centre for Evidence-Based Medicine, Nuffield Department of Primary Care Health Sciences
University of Oxford