The association between vitamin D levels and the clinical severity and inflammation markers in pediatric COVID-19 patients: single-center experience from a pandemic hospital.

In this retrospective cohort study of 103 COVID-19 positive pediatric patients aged 1-17 years in Istanbul, Turkey, a deficient serum vitamin D level [<12 ng/mL (<30 nmol/l)] was associated with clinical severity and elevated markers of inflammation.

• The prevalence of vitamin D deficiency in the asymptomatic, mild, and moderate-to-severe groups were 17.2%, 35.4%, and 70.6%, respectively.
• A comparison of patients according to vitamin D levels revealed that 55.8% of the deficient group, 17.1% of the insufficient group, and 15.8% of the sufficient group had a moderate-to-severe clinical course.
• The moderate-to-severe clinical group had significantly higher inflammation markers (CRP, procalcitonin, fibrinogen, D-dimer) and significantly lower 25 OH vitamin D levels compared to both the mild and asymptomatic groups.
• The 25 OH vitamin D level was correlated positively with the lymphocyte count, and negatively with age, CRP and fibrinogen levels.
• In a logistic regression analysis, vitamin D deficiency, D-dimer, and fibrinogen levels on admission were independent predictors of severe clinical course.

A total of 103 children (54 boys, 52.4%; 49 girls, 47.6%) with a positive SARS-CoV-2 reverse transcriptase-polymerase chain reaction (RT-PCR) test who also had a measured serum vitamin D level (25 OH vit D) were included in this study. The mean age was 12.2±4.92 years, ranging from 1–17 years. Patients with comorbidities (e.g., diabetes, asthma, tuberculosis, chronic renal failure), which may affect the clinical course of COVID-19, and those under 1 year of age were excluded from the study.

• This is a single-center study, and the findings may not be attributable to other populations.
• Genetic variability of ACE2 or the vitamin D receptor may also affect the disease’s course.
• As the anthropometric measures of all patients were unavailable, the effect of obesity on the clinical course and inflammation markers were not evaluated.

Although the effects of vitamin D on the immune system are quite complex, the available data support that adequate 25 OH vit D levels facilitate the defense process against bacterial and viral infections and prevent hyperinflammation. In this study, it has been shown that the serum vitamin D level was associated with clinical severity and markers of inflammation in children and adolescents with COVID-19. Interestingly, these associations were observed especially when there was a deficiency (i.e., 25 OH vit D <12 ng/mL). Although it has been demonstrated that vitamin D insufficiency has a role in bone metabolism, in the present study, vitamin D insufficiency was not found to be associated with disease severity or inflammation markers in COVID-19. Lastly, we suggest that considering the ongoing lockdown measures, prophylactic vitamin D supplementation may be considered especially for the adolescent age group during the COVID-19 pandemic as a health policy.

• Included in this retrospective cohort study were 103 consecutive pediatric cases presenting at Haseki Training and Research Hospital Istanbul, Turkey between March and May 2020 with SARS-CoV-2 infection confirmed by RT-PCR and with measured serum 25 OH vitamin D levels.
• Clinical data, laboratory, and imaging (chest X-ray and computed tomography) findings on admission were recorded retrospectively. COVID-19 cases were tested for a complete blood count: C-reactive protein (CRP), procalcitonin, fibrinogen, D-dimer, ferritin, calcium, phosphorus, and alkaline phosphatase (ALP).
• According to the clinical findings, patients were divided into three groups: (1) asymptomatic group: patients who underwent a PCR test due to only contact history without any complaints; (2) mild group: patients with nonspecific symptoms such as cough, fever, malaise, and myalgia; and (3) moderate-to-severe group: patients whose pneumonia was confirmed by physical examination and imaging (chest X-ray and/or computed tomography) with or without oxygen need. The moderate-to-severe group consisted of hospitalized patients. Asymptomatic and mild cases were followed by telephone or outpatient clinic visits, and none of them had a clinical deterioration.
• Serum 25 OH vit D levels were measured in hospitalized patients and outpatients. Patients were grouped according to 25 OH vit D serum levels as sufficient [>20 ng/mL (>50 nmol/l)], insufficient [12–20 ng/mL (30-50 nmol/l)], and deficient [<12 ng/mL (<30 nmol/l)].

Bayramoğlu E, Akkoç G, Ağbaş A, Akgün Ö, Yurdakul K, Selçuk Duru HN, Elevli M. The association between vitamin D levels and the clinical severity and inflammation markers in pediatric COVID-19 patients: single-center experience from a pandemic hospital. Eur J Pediatr. 2021 Mar 31:1–7. doi: 10.1007/s00431-021-04030-1. Epub ahead of print. PMID: 33788001; PMCID: PMC8009933.