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Association of Vitamin D Levels, Race/Ethnicity, and Clinical Characteristics With COVID-19 Test Results.

Take Home Message

Vitamin D deficiency and obesity increases risk of testing positive for COVID-19.

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.


  • One hundred and seventy-two (35%) individuals had vitamin D deficiency. Compared with patients who were not vitamin D deficient, patients who were vitamin D deficient were more likely to be younger (age 45.9 years vs 51.0 years), race other than White (142 of 172 [83%] vs 189 of 317 [60%]), and to have received vitamin D2 supplementation (44 of 172 [26%] vs 32 of 317 [10%]) and less likely to have received vitamin D3 supplementation (45 of 172 [26%] vs 148 of 317 [47%]).
  • The risk of having positive results in Black individuals was 2.64-fold greater with a vitamin D level of 30 to 39.9 ng/mL than a level of 40 ng/mL or greater and decreased by 5% per 1-ng/mL increase in level among individuals with a level of 30 ng/mL or greater. There were no statistically significant associations of vitamin D levels with COVID-19 positivity rates in White individuals.



  • A total of 4638 individuals (mean age 52.8 [19.5] years; 3205 [69%] women) had data for a vitamin D level within 1 year before COVID-19 testing, including 2288 (49%) Black individuals, 1999 (43%) White individuals, and 351 individuals (8%) who were another race/ethnicity (eg, Asian, Mideast Indian, >1 race).
  • Stratified by vitamin D level, 1251 individuals (27%) had less than 20 ng/mL, 1267 individuals (27%) had 20 to less than 30 ng/mL, 1023 individuals (22%) had 30 to less than 40 ng/mL, and 1097 individuals (24%) had 40 ng/mL or greater.

Things to Keep in Mind

  • This is a single center study therefore this disparity may not be the same in other locations, especially in warmer locations where access to sunlight may be more available.
  • Causality in the association between vitamin D status and the risk of COVID-19 cannot be concluded from a retrospective study.
  • Vitamin D deficiency may be a consequence associated with a range of chronic health conditions or behavioral factors that plausibly increase COVID-19 risk.
  • Data was limited to those available in the UCM electronic health record.
  • The patient sample is enriched in persons with vitamin D deficiency because of the large number of African American individuals, adults with chronic illness, and health care workers, all living in a northern city and exposed to COVID-19 during winter. Vitamin D deficiency is highly prevalent in the US but could be a smaller risk factor in other populations.


Author’s Conclusions

These findings suggest that randomized clinical trials to determine whether increasing vitamin D levels to greater than 30 to 40 ng/mL affect COVID-19 risk are warranted, especially in Black individuals.

Study Design

  • This is a retrospective cohort study conducted at an urban academic medical center (University of Chicago Medicine).
  • Electronic health records were used to gather demographic, comorbidity, laboratory, and medication data within 1 year before the date of their first COVID-19 test. Age, sex, race/ethnicity, and data to calculate BMI were also obtained from the electronic health record.
  • Multivariable analyses tested whether previously measured vitamin D level was associated with having a positive test result for COVID-19 in White individuals and in Black individuals, controlling for months and treatment changes since the vitamin D level was measured, as well as demographic characteristics and comorbidity indicators.
  • COVID-19 test status was determined by any positive COVID-19 polymerase chain reaction test result.
  • Patients were deemed to be vitamin D deficient if their most recent serum vitamin D levels within 1 year before their first COVID-19 tests were < 50 nmol/L for 25-hydroxycholecalciferol or < 43.2 pmol/L for 1,25-dihydroxycholecalciferol.
  • Vitamin D treatment was defined by report in the electronic health record of vitamin D either in the patient medication list or prescription orders.
  • Investigators combined the data on last vitamin D level measurements with changes in treatment after that last vitamin D level to assign each patient to 1 of 4 categories,

reflecting their likelihood of being vitamin D deficient at the time of COVID-19 testing: likely deficient (last level deficient and treatment not increased), likely sufficient (last level not deficient and treatment not decreased), and 2 groups with uncertain deficiency (last level deficient and treatment increased, and last level not deficient and treatment decreased).

  • ICD-10-CM codes for comorbidities were identified in the medical record over a 2-year period and include, hypertension, diabetes, chronic pulmonary disease, pulmonary circulation disorders, depression, immunosuppression, liver disease, and chronic kidney disease.



Meltzer DO, Best TJ, Zhang H, Vokes T, Arora VM, Solway J. Association of Vitamin D Levels, Race/Ethnicity, and Clinical Characteristics With COVID-19 Test Results. JAMA Netw Open. 2021;4(3):e214117. doi:10.1001/jamanetworkopen.2021.4117.

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Research Summaries

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

Changes in 25‐hydroxyvitamin D levels post‐vitamin D supplementation in people of Black and Asian ethnicities and its implications during COVID‐19

Vitamin D insufficiency in COVID-19 and influenza A, and critical illness survivors: a cross-sectional study

Take Home Message Vitamin D deficiency/insufficiency was present in majority of hospitalized patients with COVID-19 or influenza A and correlated with severity and persisted in critical illness survivors at concentrations expected