Table 1.
Characteristics of included studies for the systematic review and meta-analysis.
| References | Country | Sample size |
Study design |
Participants | Outcome | Results and conclusion | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1. Meltzer et al. (27) | USA | 499 | Cohort | VDD: 178 Vitamin-D sufficient: 321 |
COVID-19 infection | VDD (RR = 1.77) are at higher risk of Covid 19 infection as compared to vitamin D sufficient, with predicted COVID-19 rates in the vitamin D deficient group of 21.6%(95%CI [14.0–29.2%]) vs. 12.2%(95% CI [8.9–15.4%]) in the vitamin D sufficient group | ||||
| 2. Raharusun et al. (30) | Indonesia | 780 | Cohort | COVID_19 patients | COVID-19 related mortality | The odds of death were higher in cases with insufficient Vitamin D status (OR = 7.63; p < 0.001) as compared to a normal level. When compared to cases with normal Vitamin D status, death was approximately 10.12 times more likely for Vitamin D deficient cases (OR = 10.12; p < 0.001) | ||||
| Vitamin D Covid-19 case (400) Death due to COVID-19 (380) | ||||||||||
| Normal (= 388) | 372 (93.0%) | 16 (4.2%) | ||||||||
| Insufficient (213) | 26 (6.5%) | 187 (49.1%) | ||||||||
| VDD: (179) | 2 (0.5%) | 177 (46.7%) | ||||||||
| 3. Merzon et al. (22) | Israel | 7,807 | Cohort | Covid-19 infected individuals | Vitamin D status among cases and Controls | Mean vitamin D level was significantly lower in COVID-19 patients than controls [19.00 ng/mL (95% CI: 18.41–19.59) vs. 20.55 (95% CI 20.32–20.78)]. Low plasma 25(OH) D level appears to be an independent risk factor for COVID-19 infection and hospitalization | ||||
| 4. Hastie et al. (15, 25) | England | 449 | Cohort | COVID 19 patients | COVID-19 infection | There was no a potential link between vitamin D concentrations and risk of COVID-19 infection | ||||
| 5. D'Avolio et al. (14) | Switzerland | 187 | cohort | SARS-CoV-2 PCR-positive | 25-hydroxyvitamin D (25(OH) D) level among the cases and control group | Significantly lower 25(OH)D levels were found in COVID-19 patients (median value 11.1 ng/mL) patients compared with control groups (24.6 ng/mL). Vitamin D3 supplementation would be useful in the treatment of COVID-19 infection, in preventing more severe symptomatology and/or in reducing the presence of the virus in the upper respiratory tract and making the patients less infectious |
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| 6. Abdollahi et al. (32) | Iran | 402 | Case-control | Covid-19 positive: 201 Covid-19 Negative: 201 |
Status of Vitamin D among the control and case groups | The level of serum 25(OH) vitamin D was significantly lower in COVID-19 positive patients (p = 0.02) and the results demonstrated that there was a significant relationship between the levels of serum 25(OH) vitamin D and the vulnerability to COVID-19 | ||||
| Cases | Controls | |||||||||
| Insufficient 162 (80.5%) | 132 (65.67%) | |||||||||
| Sufficient 39 (19.4%) | 69 (34.32%) | |||||||||
| Vitamin D deficiency is one of the main predisposing factors associated with the vulnerability to coronavirus infection in the Iranian population | ||||||||||
| 7. Ye et al. (31) | China | 142 | Case-control | COVID-19 positive: 62 COVID-19 negative: 80 |
Status of vitamin D and severity of the diseases | Significantly higher rates of VDD were found in COVID-19 cases (41.9%) compared to control group (11.1%) | ||||
| Cases | Control | Mild/mod | Severe | |||||||
| Deficient | 26 (42) | 15 (19) | 18 (36) | 8 (80) | ||||||
| Non-deficient | 36 (58) | 65 (81) | 32 (64) | 2 (20) | ||||||
| VDD was a risk factor for COVID-19, especially for severe/critical cases | ||||||||||
| 8. Hernández et al. (20) | Spain | 394 | Case-control | Covid-19 positive: 197 Covid-19 Negative: 197 |
Vitamin D status and Covid-19 infection | Cases | Control | |||
| Deficient | 82.2% | 47.2% | ||||||||
| Sufficient | 17.8% | 52.8% | ||||||||
| Covid-19 positive patients had a lower vitamin D level than the control groups. Moreover, 25OHD levels are lower in hospitalized COVID-19 patients than controls. Serum 25OHD levels are significantly lower in hospitalized COVID-19 patients than in controls of similar age and sex, and that these differences remain significant even after adjusting for the main confounding factors. Patients with vitamin D supplements had an overall lower percentage of the combined severity endpoint and ICU admissions, as well as a shorter length of hospital stay, although these data did not reach statistical significance |
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| 9. Kaufman et al. (26) | USA | 79,381 | Case-control | Covid-19 positive: 7,883 Covid-19negative: 71,498 |
Vitamin D status and Covid-19 infection | COVID-19 | Positive | Negative | ||
| Deficient: | 4,899 | 34,291 | ||||||||
| Adequate: | 2,984 | 37,207 | ||||||||
| SARS-CoV-2 positivity is strongly and inversely associated with circulating 25(OH) D levels, a relationship that persists across latitudes, races/ethnicities, both sexes, and age ranges. Our findings provide impetus to explore the role of vitamin D supplementation in reducing the risk for SARS-CoV-2 infection and COVID-19 disease | ||||||||||
| 10. Yilmaz and Sen (21) | Turkey | 85 | Case-control | Covid-19 positive: 40 Covid-19 Negative: 45 |
Vitamin D status and Covid-19 infection | Cases | Control | |||
| Deficient: | 29 (72.5%) | 29 | ||||||||
| Normal: | 11 (27.5%) | 16 | ||||||||
| Patients with COVID-19 had significantly lower vitamin D levels 13.14 μg/L (4.19–69.28) than did the controls 34.81 (3.8–77.42) μg/L (p < .001) | ||||||||||
| 11. Maghbooli et al. (29) | Iran | 235 | Cross-sectional | COVID-19 Patients | COVID related morbidity and mortality | There was a significant association between vitamin D sufficiency and reduction in clinical severity, inpatient mortality, serum levels of C-reactive protein (CRP), and an increase in lymphocyte percentage. Only 9.7% of patients older than 40 years who were vitamin D sufficient succumbed to the infection compared to 20% who had a circulating level of 25(OH)D <30 ng/mL The severity of clinical outcomes from COVID-19 and mortality was dramatically reduced in patients who were vitamin D sufficient Improving vitamin D status in the general population and particularly hospitalized patients have a potential benefit in reducing the severity of morbidities and mortality associated with acquiring COVID-19 |
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| 25OHD ≥30 (N = 77) | 25OHD < 30 (N = 158) | |||||||||
| Inpatient mortality | 9% (7) | 20% (26) | ||||||||
| Severity-critical | 63.6% (49) | 77.2% (122) | ||||||||
| 12. De Smet et al. (23) | Belgium | 186 | Crossectional | SARS-CoV-2-infected patients | Analysis of 25(OH)D in COVID-19 patients | COVID-19 patients showed lower median 25(OH) D (18.6 ng/mL, IQR 12.6–25.3, vs. 21.5 ng/mL, IQR 13.9–65 30.8;) and higher VDD rates (58.6 vs. 45.2%) | ||||
| 13. Panagiotou et al. (24) | England | 134 | Interim audit | Patients with COVID-19 | Level of vitamin D among COVID-19 patients | A higher prevalence of VDD was observed in patients requiring intensive therapy unit compared to patients managed on medical wards. While mean serum 25(OH) D levels were comparable (p = 0.3), only 19% of ITU patients had 25(OH) D levels greater than 50 nmol/L vs. 39.1% of non-ITU patients (p = 0.02) | ||||
| 14. Alguwaihes et al. (28) | Saudi Arabia | 439 | Crossectional study | COVID-19 patients | VDD and mortality | 74.7% of COVID-19 patients had VDD, and patients with 25(OH) D < 12.5 nmol/l were 7 times at risk of mortality [AHR 7.0 (CI 1.7–28.2)]. VDD was significant predictors of mortality among hospitalized Covid-19 patients | ||||