The potential therapeutic effect of vitamin D supplementation for management of SARS-COV-2: a systematic review/meta-analysis

Background: vitamin D deficiency has long been associated with decreased immune function and can lead to viral infections. Studies have shown that vitamin D deficiency is associated with an increased risk of COVID-19 infection. However, it is unclear whether treatment with vitamin D can reduce the associated risk of COVID-19 infection. Objective: the current meta-analysis aimed to determine whether vitamin D supplementation had a positive or negative impact on COVID-19 patients. Materials and methods: for this systematic review and meta-analysis, we searched the following databases; CENTERAL, Medline (PubMed), Web of Science, EMBASE and Egyptian Knowledge Bank (EKB, for studies published till February 20, 2022, using key terms. Besides, reference lists of relevant studies were identified. We considered randomized trials (RCTs) and cohort studies as potentially eligible when patients were tested for SARS-CoV-2 infection and received vitamin D supplementation versus a placebo or standard-of-care control. We identified a total of 718 articles, of which 4 RCTs and 3 cohort studies which meet eligible criteria. The seven studies included in our meta-analysis involved 1238 subjects. We considered 7 outcomes to be measured in our meta-analysis which are duration of COVID-19 illness till recovery, need for O2 therapy, need for ICU admission, need for artificial ventilation, fatal prognosis, time to negative PCR and need for hospitalization. Results: vitamin D supplement decreased the period of hospital stay in SARS-CoV2 positive patients. There was no clear protective effect of vitamin D supplementation on the need for oxygen therapy. There was no reduction on need for ICU admission in SARS-CoV2 patients treated with vitamin D supplementation. There was a significant reduction on need for artificial ventilation in patients treated with vitamin D supplementation. Our meta-analysis showed that there is no reduction on fatal prognosis in patients treated with vitamin D supplementation. Only one RCT evaluated time to negative PCR; this study was conducted in India and showed that vitamin D supplementation helped to achieve SARS-CoV-2 RNA negativity in greater proportion of COVID-19 patients with vitamin D supplementation. Conclusion: administration of vitamin D after diagnosis of SARS-CoV-2 infection reduces the period of hospital stay and also reduces the need for artificial ventilation.