Review the Research
Get summaries of key research on vitamin D and COVID-19
Vitamin D Deficiency Is Associated with COVID-19 Incidence and Disease Severity in Chinese People.
Take Home Message
Significantly lower serum 25(OH)D concentrations were found in severe COVID-19 patients from Wuhan, China compared to non-severe patients. Vitamin D deficiency (<30 nmol/L) was associated with COVID-19 severity, after adjusting for several potential confounders, such as age, sex, comorbidities, BMI and smoking status.
The aim of this study was to explore an association between the serum vitamin D level, obesity, and underlying health conditions, as well as the vulnerability to COVID‐19 in the Iranian population.
- After adjusting for age, sex, comorbidities and BMI, serum 25(OH)D concentrations
were significantly lower among COVID-19 patients than the 2018–2019 controls (27.7 nmol/L vs. 31.8 nmol/L).
- In the COVID-19 group, 261 (77.9%) patients were categorized as non-severe and 74 (22.1%) were categorized as severe. The severe COVID-19 patients were significantly
older and male (62.5 years, range 51.0-75.3 years; 58.1% male) than the non-severe COVID-19 patients (54.0 years, range 40.0–62.0 years; 40.2% male).
- Statistical analysis (multivariate regression) showed that male sex, advanced age (≥65 y) and vitamin D deficiency (<30 nmol/L) were significantly associated with COVID-19 severity.
Three-hundred thirty-five consecutive patients diagnosed with COVID-19 who were admitted to Tongji Hospital (Wuhan, China) between February 27, 2020 and March 21, 2020.
Things to Keep in Mind
- The cross-sectional study design may be a major limitation. Although vitamin D deficiency was associated with COVID-19 incidence and disease severity, causality cannot be established. Better-designed clinical trials are warranted in the future.
- A sufficient number of vitamin D measurements could not be obtained from population wide testing during the study period (2020) due to the COVID-19 outbreak. Thus, the authors selected the 2018–2019 cohort as representative of the vitamin D status of the general public.
- Since the study group was predominantly Asian, the results may not be applicable to populations with a significantly different ethnic makeup.
The study showed that individuals with vitamin D deficiency were more common among patients with COVID-19 infection and severe illness. Interventional trials
would be helpful in clarifying the role of vitamin D in COVID-19 infection and disease severity.
- A cross-sectional, retrospective study that analyzed 335 COVID-19 patients (median age =56.0 years; range=43.0–64.0 years) who were admitted to the Wuhan Tongji Hospital during the study period. Blood samples were obtained for all COVID-19 patients on admission and serum 25(OH)D concentrations were measured. Data regarding demographic characteristics, treatment, ventilation condition, and outcome were retrospectively reviewed from electronic medical records.
- An age- and sex-matched population of 560 individuals (median age=55 years; range= 49.0–60.0 years) who underwent a physical exam during 2018-2019 and had serum 25(OH)D concentrations measured during the same period as the COVID-19 positive patients (27 February to 21 March) was used as a comparison.
- Severity of COVID-19 was determined based on the level of respiratory involvement:
- Mild: mild symptoms with no signs of pneumonia on imaging;
- Moderate: fever, respiratory symptoms with radiological evidence of pneumonia;
- Severe (meeting any of the following): respiratory distress, respiratory rate ≥30 breaths/min, hypoxemia, oxygen saturation (SpO2) ≤93% (at rest), or lung infiltrates of >50% within 24–48 h; and
- Critical (meeting any of the following): respiratory failure requiring mechanical ventilation, shock, or multiple organ dysfunction requiring intensive care unit monitoring and treatment.
- Mild and moderate cases were classified into the non-severe group, while severe and critical cases were classified into the severe group.
- Patients were categorized as vitamin D–deficient (<30 nmol/L) or
non-vitamin D–deficient (≥30 nmol/L).
- BMI was calculated as kg/m2.