Vitamin D on COVID-19 Patients During the Pandemic, 2022. A Systematic Review and Meta-Analysis

Efficacy of vitamin D replacement therapy on 28 cases of myalgic encephalomyelitis/chronic fatigue syndrome after COVID-19 vaccination

BACKGROUND

Prolonged symptoms have been reported following both COVID-19 infection and vaccination, with some cases leading to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Of 80 patients presenting to our hospital with postvaccination syndrome, 28 met the diagnostic criteria for ME/CFS. We conducted a retrospective study on these 28 patients.

METHODS

We measured serum 25-hydroxyvitamin D levels in 28 patients who developed ME/CFS after COVID-19 vaccination between August 2022 and February 2024. Vitamin D replacement therapy included dietary counseling, sun exposure recommendations, and oral vitamin D supplementation. We evaluated changes in blood vitamin D levels and symptom improvement.

RESULTS

At initial visit, 27 of 28 patients diagnosed with ME/CFS had insufficient or deficient serum 25-hydroxyvitamin D levels (16 ± 4 ng/mL, mean ± SD). Following vitamin D replacement therapy, we observed an increase in blood vitamin D levels (28 ± 5 ng/mL) associated with a decrease in ME/CFS diagnostic symptoms (from 10.3 ± 2.1 to 3.3 ± 2.0). Notably, 23 of 28 patients (82%) no longer met ME/CFS diagnostic criteria after the therapy. Among the symptoms, sleep problems showed the most improvement (71%), followed by autonomic symptoms (68%).

CONCLUSIONS

For patients developing ME/CFS after COVID-19 vaccination with insufficient or deficient vitamin D levels, appropriate vitamin D replacement therapy under medical guidance may lead to symptomatic relief. We are preparing a randomized controlled trial to evaluate the efficacy of vitamin D replacement therapy in individuals with ME/CFS who have developed vitamin D deficiency following COVID-19 infection or vaccination.

Association Between Vitamin D and COVID-19-Related Outcomes: An Umbrella Review of Meta-Analyses

CONTEXT

COVID-19 remains globally pandemic, and although several meta-analyses have explored the association between vitamin D and COVID-19 relative to clinical outcomes, a unified view has not yet emerged.

OBJECTIVE

To summarize the evidence for associations between vitamin D levels and COVID-19-related clinical outcomes and to assess the strength and validity of these associations.

DATA SOURCES

PubMed, Embase, Web of Science, Scopus, and the Cochrane Database of Systematic Reviews databases were searched from January 1, 2020, to June 15, 2024.

DATA EXTRACTION

Two reviewers independently extracted data and assessed study quality.

DATA ANALYSIS

Low vitamin D levels increased the risk of infection by 1.26- to 2.18-fold, the risk of severe illness by 1.50- to 5.57-fold, the risk of intensive care unit (ICU) admission by more than 2-fold, and the risk of death by 1.22- to 4.15-fold. In addition, patients with vitamin D deficiency had an average increase in length of hospital stay of 0.54 days compared with patients with high vitamin D levels. Overall, vitamin D supplementation may reduce severity (eg, ICU admissions, need for mechanical ventilation) and shorter length of hospital stay but has a nonsignificant effect on infection and mortality rates. In addition, there were significant differences in vitamin D levels between individuals testing positive for COVID-19 and those testing negative (mean difference [MD] = -3.22 ng mL-1; 95% CI, -5.18 to -1.25), those with severe cases and those with mild cases (MD = -4.60 ng mL-1; 95% CI, -5.49 to -3.71), and nonsurvivors and survivors of COVID-19 infection (MD = -6.59 ng mL-1; 95% CI: -8.94 to -4.24).

CONCLUSIONS

Low vitamin D levels are associated with higher infection rates, more severe disease, and higher mortality rates among individuals with COVID-19, whereas vitamin D supplementation may reduce patients' disease severity. The beneficial effects on infection rates and mortality remain to be further explored, however, in higher-quality, randomized controlled studies. Nonetheless, caution is warranted because the methodological quality of most meta-analyses and the level of evidence for most outcomes are very low.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration No. CRD42022385036.

Pharmacological evaluation of vitamin D in COVID-19 and long COVID-19: recent studies confirm clinical validation and highlight metformin to improve VDR sensitivity and efficacy

Nearly four years after its first appearance, and having gone from pandemic to endemic, the SARS-CoV-2 remains out of control globally. The purpose of this study was to evaluate the clinical efficacy of vitamin D (VD) in COVID-19 and long COVID-19, explain the discrepancy in clinical outcomes and highlight the potential impact of metformin on VD efficacy in recent articles. Articles from January 2022 to August 2023 were selected for this review. The objective of this study was achieved by reviewing, analyzing, and discussing articles demonstrating (1) the mechanism of action of VD (2) observational or randomized clinical trials (RCTs) that support or not the beneficial clinical effects of VD in COVID-19 or long COVID. (3) genetic and non-genetic reasons for the variation in the effects of VD. Articles were collected from electronic databases such as PubMed, Scopus, MEDLINE, Google Scholar, Egyptian Knowledge Bank, Science Direct, and Cochrane Database of Systematic Reviews. Twenty three studies conducted in vitro or in animal models indicated that VD may act in COVID-19 through protecting the respiratory system by antimicrobial peptide cathelicidins, reducing lung inflammation, regulating innate and adaptive immune functions and up regulation of autophagy gene activity. Our review identified 58 clinical studies that met the criteria. The number of publications supporting a beneficial clinical activity of VD in treating COVID-19 was 49 (86%), including 12 meta-analyses. Although the total patients included in all articles was 14,071,273, patients included in publications supporting a beneficial role of VD in COVID-19 were 14,029,411 (99.7%). Collectively, extensive observational studies indicated a decisive relationship between low VD levels and the severity of COVID-19 and mortality outcomes. Importantly, evidence from intervention studies has demonstrated the effectiveness of VD supplements in treating COVID-19. Furthermore, the results of 4 observational studies supported the beneficial role of VD in alleviating symptoms of long COVID-19 disease. However, eight RCTs and one meta-analysis of RCTs may contain low-grade evidence against a beneficial role of VD in COVID-19. Twenty-five articles have addressed the association between VDR and DBP genetic polymorphisms and treatment failure of VD in COVID-19. Impaired VDR signaling may underlie the variability of VD effects as non-genetic mechanisms. Interestingly, in recent studies, metformin has a beneficial therapeutic role in COVID-19 and long COVID-19, possibly by improving AMPK signaling of the VDR and enhancing the efficacy of the VD. In conclusion, evidence has been significantly strengthened over the past 18 months, with several meta-analyses and RCTs reporting conclusive beneficial effects of VD supplementation against COVID-19 and highlighting metformin to improve VDR sensitivity and efficacy in treating COVID-19 and long COVID-19.