Recommendation for research

Recommendation for research

We have made the following recommendation for research.

Treating COVID-19

What is the clinical effectiveness of vitamin D supplements for treating COVID‑19 in adults, young people and children? Randomised controlled trials in all care settings with a minimum 8‑week follow up are recommended. There should be a particular focus on subgroup analyses including, but not limited to, age (such as over 75 years), ethnicity (for example, black, Asian and minority ethnic groups) and comorbidities (for example, obesity) that are associated with poorer outcomes in people with COVID‑19.

Suggested PICO (population, interventions, comparators, outcomes)




Adults, young people and children with confirmed COVID‑19.

Evidence specific to the following groups should be obtained:

  • people with more severe COVID‑19 or longer duration of COVID‑19

  • older people (over 75)

  • black, Asian and minority ethnic groups

  • people with comorbidities (for example, obesity)

  • people with low vitamin D status.

Effectiveness of vitamin D treatment in these populations should be explored wherever possible using:

  • subgroup analyses

  • sensitivity analyses.

Trials should be adequately powered to assess the effectiveness in these groups.


Vitamin D or vitamin D derivatives (all dosages, formulations and routes of administration).

Note: Vitamin D as an adjunctive treatment will be included if other treatments are balanced out in the control arm.


Placebo or no treatment (in addition to standard care).

Note: for vitamin D supplementation as an adjunctive treatment, the comparator will be the index treatment. For example: vitamin D plus treatment X versus treatment X.



  • mortality (including all-cause mortality and COVID‑19 related mortality)

  • intensive care unit admission

  • hospitalisation.


  • use of ventilation (including non-invasive and invasive)

  • infection cure rates (laboratory, or virologically or radiographically confirmed)

  • time to clinical cure

  • duration of hospital or intensive care unit admission

  • complications (primary or secondary to COVID‑19)

  • reduction in symptoms, symptom severity or both

  • adverse effects and safety

  • tolerability

  • long-term effects of COVID‑19.

Preventing COVID-19

The panel discussed the importance of research into the clinical effectiveness of vitamin D for preventing SARS‑CoV‑2 infection (and subsequent COVID‑19).

For a short explanation of why we made a research recommendation about research into vitamin D for treating COVID‑19, and a discussion of research into vitamin D for preventing COVID‑19, see the rationale section on recommendations.

Full details of the evidence are in the evidence review.