Table 1.
Basic characteristics of the included systematic reviews
| Serial number | Authors | Title | Country | No of studies included | Types of studies included | Total population |
|---|---|---|---|---|---|---|
| 1 | Chen et al., Oct 2012114 | Low vitamin D levels do not aggravate COVID-19 risk or death, and vitamin D supplementation does not improve outcomes in hospitalized patients with COVID-19: A meta-analysis and GRADE assessment of cohort studies and RCTs | China | 13 | Cohort studies = 11, Randomized control Trials = 2 | 5 36 418 |
| 2 | Grove et al., May 202115 | Association between vitamin D supplementation or serum vitamin D level and susceptibility to SARS-CoV-2 infection or COVID-19 including clinical course, morbidity and mortality outcomes? A systematic review | UK | 4 | Cross-sectional study = 1, retrospective cohort study = 1, ecological country study = 1, case-control survey = 1 | 2042 |
| 3 | Hariyanto et al., June 202116 | Vitamin D supplementation and Covid-19 outcomes: A systematic review, meta-analysis and meta-regression | Indonesia | 11 | Retrospective cohort studies = 4, Open-label randomized clinical trial = 1, Prospective cohort studies = 2, Cross-sectional studies = 3, double-blind randomized clinical trial = 1 | 2265 |
| 4 | Nikniaz et al., Jan 202117 | The impact of vitamin D supplementation on mortality rate and clinical outcomes of COVID-19 patients: A systematic review and meta-analysis | Iran | 4 | Randomized control trials = 2, Quasi Experimental trials = 2 | 259 |
| 5 | Pal et al., June 202118 | Vitamin D supplementation and clinical outcomes in COVID 19: a systematic review and meta-analysis | India | 13 | Randomized control trials = 3, Observational studies = 10 | 2933 |
| 6 | Rawat et al., June 202119 | Vitamin D supplementation and COVID-19 treatment: A systematic review and meta-analysis | India | 5 | Randomized control trials = 3, Quasi experimental studies = 2 | 467 |
| 7 | Shah et al., May 202120 | Vitamin D supplementation, COVID-19 and disease severity: a meta-analysis | India | 3 | Randomized control trials = 2, retrospective case-control study = 1 | 532 |
| 8 | Stroehlein et al., May 202121 | Vitamin D supplementation for the treatment of COVID‐19: a living systematic review | Germany | 3 | Randomized control trials = 3 | 356 |
| 9 | Tentolouris et al., Dec 202122 | The effect of vitamin D supplementation on mortality and intensive care unit admission of COVID-19 patients. A systematic review, meta-analysis and meta-regression | Greece | 10 | Randomized control trials = 2, non-randomized trials = 8 | 2078 |
| 10 | Vaughan et al., Oct 202123 | Changes in 25‐hydroxyvitamin D levels post‐vitamin D supplementation in people of Black and Asian ethnicities and its implications during COVID‐19 pandemic: A systematic review | UK | 8 | Randomized control trials = 8 | 1108 |