Does Serum Vitamin D Level Affect COVID-19 Infection and Its Severity?-A Case-Control Study

Abstract

Background

As effective medication to treat COVID-19 is currently unavailable, preventive remedies may be particularly important.

Objective

To examine the relationship between serum 25-hydroxy vitamin D (25(OH)D) level and COVID-19 infection, its severity, and its clinical case characteristics.

Methods

This case-control study compared serum 25(OH)D levels and rates of vitamin D deficiency (VDD) between 80 healthy controls and 62 patients diagnosed with COVID-19 and admitted to Guangxi People’s Hospital, China, 2/16/2020–3/16/2020. Cases were categorized into asymptomatic, mild/moderate, and severe/critical disease. Logistic regression analysis was conducted to examine the associations between 25(OH)D level, or VDD, and case status/severity of COVID-19 while controlling for demographics and comorbidities. A threshold level of vitamin D for conveying COVID-19 risk was estimated.

Results

Severe/critical COVID-19 cases were significantly older and had higher percentages of comorbidity (renal failure) compared to mild cases. The serum 25(OH)D concentration in COVID-19 patient was much lower than that in healthy control. And 25(OH)D level was the lowest in severe/critical cases, compared with mild cases. In further, significantly higher rates of VDD were found in COVID-19 cases (41.9%) compared to healthy controls (11.1%). And VDD was the greatest in severe/critical cases (80%), compared with mild cases (36%). These statistically significant associations remained even after controlling for demographics and comorbidities. A potential threshold of 25(OH)D (41.19 nmol/L) to protect against COVID-19 was identified.

Conclusion

Elderly and people with comorbidities were susceptible to severe COVID-19 infection. VDD was a risk factor for COVID-19, especially for severe/critical cases. While further confirmation is needed, vitamin D supplementation may have prevention or treatment potential for COVID-19 disease.

Keywords:

• COVID-19
• vitamin D deficiency
• severity
• risk factor

Acknowledgments

We acknowledge all medical staff involved in the diagnosis and treatment of patients with COVID-19 in Guangxi. We thank Yiyun Huang, BS, Xiaojuan Luo, MM, and Yuanyuan Zeng, MM, Department of Nephrology, The People’s Hospital of Guangxi Zhuang Autonomous Region, for collecting the data and preparing the Table. None of these individuals received compensation for their contributions.

Authors’ contributions

K. Ye, S. Lin, F. Xu. Designed research; F.Tang, X.Liao, G. Huang, C. Chen, N. Tang conducted research; H. Xiao, X. Liao performed statistical analysis; F. Tang, X. Liao, M. Deng wrote the paper; Z. Qin, X. Peng, X. Liu, L. Ning, B. Wang, M. Li, J. Yang provided essential technical and material support; F. Xu, S. Lin, J. Yang, K. Ye had primary responsibility for final content. All authors read and approved the final manuscript.

Disclosure statement

All authors have no conflict of interest.

Additional information

Funding

This work was supported by the Guangxi Critical Infectious Disease Center (2020281) and Nanning Science and Technology Foundation (2018030).