Re. “Cohort study to evaluate the effect of vitamin D, magnesium, and vitamin B₁₂ in combination on progression to severe outcomes in older patients with coronavirus (COVID-19)”: Authors' response

Dear Dr. Yue Suo,

We appreciate your keen interest in our paper [1], and we agree that both concerns are reasonable and valid [2]. In fact, we have listed both in the discussion on the limitations of the study. In view of the control group being older with a trend of having more comorbidities, especially diabetes, we included a subgroup analysis that retained the benefits of DMB, although statistical significance could not be demonstrated, considering the small number of patients in the subgroup analysis. Regarding the nutritional status of the patients, we were not able to include systematic biological measures as the study was conducted under difficult dynamic circumstances.

Nevertheless, the overall result is indicative of a potential benefit of giving a combination of vitamin D, magnesium and vitamin B₁₂ to improve the severity of COVID-19, but this will require further large-scale random controlled trials to confirm.