Review the Research

Get summaries of key research on vitamin D and COVID-19

Is vitamin D deficiency a risk factor for COVID‐19 in children?

Take Home Message

There is a potential connection between vitamin D level and COVID-19, but more studies in children are needed before any conclusions can be drawn.


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.


  • There were statistically significantly lower serum phosphorus level and vitamin D levels in the COVID‐19 diagnosed patient group.
  • 18 children in the COVID‐19 patient group had vitamin D deficient values and 11 children had vitamin D insufficient values. Eight children in the healthy group had vitamin D deficient values and three children had vitamin D insufficient values.
  • The symptom of fever (34.5%) was significantly higher in Group 1 (deficient and insufficient) than in Group 2 (0%). There were significantly lower levels of vitamin D and serum phosphorus in Group 1 than those in Group 2. No significant difference was found between other clinical and laboratory parameters between the groups.
  • There was a negative correlation found between fever symptom and vitamin D level. However, no significant correlations were found between other clinical parameters and vitamin D level.



40 patients (aged 1 month to 18 years) who were diagnosed with COVID‐19 and hospitalized, 45 healthy matched control subjects with vitamin D levels who had been seen at the outpatient clinic of Dicle University Faculty of Medicine, Diyarbakir, Turkey. Patients and controls with comorbidities were not included.

Things to Keep in Mind

  • This is a single center study in Turkey, therefore generalizations to other populations may not be appropriate.
  • This is a retrospective study from medical records and is thus limited.
  • The study only includes patients over a short period of time, results over a year or longer including multiple seasons may be more accurate.


Author’s Conclusions

There are significantly lower levels of vitamin D in children with COVID‐19 than those in the control group. However, we do not assume that vitamin D plays a role in the physiopathology of COVID‐19 whether there is really an association between vitamin D deficiency and COVID‐19 needs to be further addressed. Deficient/insufficient Vitamin D levels are associated with fever. Since there were no reported cases of death in our study, the relationship with vitamin D deficiency and mortality could not be evaluated. More studies are needed in children for evaluation of the association between vitamin D with clinical and laboratory findings of the disease and its effect on mortality.

Study Design

  • The was a retrospective chart review.
  • The age of admission, clinical and laboratory data, and 25‐hydroxycholecalciferol (25‐OHD) and parathormone (PTH) levels were recorded.
  • Those with 25‐OHD level less than 12 ng/ml were considered as vitamin D deficient, those between 12 and 20 ng/ml were considered vitamin D insufficient and those with greater than 20 ng/ml were considered to have a normal vitamin D.
  • Patients diagnosed with COVID‐19 were divided into two groups. Those with vitamin D levels which are below 20 ng/ml were determined as Group 1 and those with ≥20 ng/ml as Group 2, and clinical and laboratory variables between the two groups were compared.
  • The severity of the disease was classified as asymptomatic, mild, moderate, severe, and critical according to the clinical characteristic, laboratory results, and chest radiography findings.


Yılmaz K, Şen V. Is vitamin D deficiency a risk factor for COVID-19 in children? Pediatr Pulmonol. 2020 Dec;55(12):3595-3601. doi: 10.1002/ppul.25106. Epub 2020 Oct 13. PMID: 33017102; PMCID: PMC7675606.

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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