Vitamin D and COVID-19: First results are out!

End of May 2020, 7 clinical trials were examining the effect of vitamin D supplementation on COVID-19 outcomes. Today, October 6, 2020, 26 clinical trials are registered, at different stages of execution, with only one having already published results. So I dove into the findings, very eager to find out if they supported the hypothesis that Vitamin D supplementation could prevent or mitigate COVID-19 symptoms, morbidity and mortality. The study was conducted in Spain, at the Reina Sofia University hospital and included seventy-six COVID-19 patients admitted with acute respiratory infection. Researchers investigated whether supplementing patients with a high dose of Vitamin D would reduce the need for admission to the ICU as well as the risk of death.

Keeping in mind that the study is a pilot trial with some limitations duly explained by the authors, results are promising and give solid ground to explore the sunshine vitamin as a treatment of COVID-19 patients, at least concomitantly administered with standard care.  

Overall, the authors report that out of 50 patients treated with vitamin D, only one was admitted to the ICU with no reported deaths. In the unsupplemented group, 13 patients out of 26 required admission to the ICU, with 2 reported deaths. 

While these results seem to be handing us the solution to the COVID-19 pandemic on a silver platter, science is always a little more complicated than it seems, and in the case of this study, here is why:

First, the study was an open label trial, meaning that patients assigned to Vitamin D knew what they were being administered. In addition, there was no placebo involved, just a “supplemented” versus “unsupplemented” group approach. 

Second and more importantly, although the trial was randomized, this did not eliminate some important differences between the two groups. In fact, 58% of the patients in the unsupplemented group had high blood pressure versus only 24% in the supplemented group. Knowing that high blood pressure is a risk factor for COVID infection and complications, it could have played a role in the higher rate of admissions to the ICU for the unsupplemented group. The same applies to diabetes as there were fewer diabetic patients (6%) in the Vitamin D group than the unsupplemented group (19%). Knowing that these confounders can seriously challenge the results, the authors calculated the relative risk of ICU admission while statistically adjusting for the rates of hypertension and diabetes, in order to verify the efficacy of Vitamin D, had these variables been equal between groups. The adjusted numbers still confirm the lower risk of ICU admission for patients with vitamin D supplementation versus unsupplemented patients

In conclusion, this pilot trial does give us a preliminary look into the promising potential of Vitamin D in the treatment of COVID-19 infections. The need for a larger, properly matched trial has been addressed by the authors of the published paper who announced the launch of the COVIDIOL study that will run across 15 Spanish hospitals to confirm the beneficial effect of Vitamin D on clinical outcomes of patients requiring hospitalization.

In the meantime, 25 other clinical trials are underway, with results expected to be out starting December 2020. While I anxiously wait to see the scientific consensus on vitamin D, I will continuously update my blog with new findings as they come in.

Amira Kassis, PhD

Scientific consultant