Association between the Vitamin D Deficiency and Recurrence of Respiratory Tract Infections in Children

Background: Respiratory tract infections (RTIs) continue to be one of the major contributors to morbidity among children. Vitamin D has a significant immunomodulatory activity and its deficiency has been linked with a growing number of recurrent respiratory tract infections in children

Objective: This study aims to evaluate the association between serum vitamin D deficiency and recurrent respiratory tract infections among pediatric patients.

Methodology: A prospective cohort study was conducted in the Department of Pediatric Medicine, Dr. MR Khan Shishu Hospital & Institute of Child Health, Dhaka, Bangladesh, between February 2025 and January 2026 with a total of 100 children (1-12 years) with recurrent respiratory tract infections. 25-hydroxy-vitamin D was determined and classified as deficient (<20 ng/mL), insufficient (20–29 ng/mL), and sufficient (≥30 ng/ mL). All data was collected manually and later analyzed in SPSS version 25.0.

Results: The mean age of the participants was 5.8 ± 2.7 years with a majority being male (56%) and living in the rural area (61%). Overall, 58% of children were vitamin D deficient and 4–6 years (20%) of age group has highest deficiency. 39% children had 5–6 RTI episodes each year and children with vitamin D deficiency had significantly higher mean infection episodes per year (6.8 ± 1.9) with a statistically significant association (p<0.001). There were significantly different mean vitamin D levels in severe respiratory infections (15.6 ± 4.8 ng/mL) compared to moderate and mild infections (p<0.001). The seasonal variation analysis showed that the highest mean number of RTI episodes occurred during winter (p=0.003).

Conclusion: In our context, clinical and biological criteria were the only truly usable indicators. Probabilistic antibiotic therapy remains the main strategy to reduce neonatal mortality, which remains unacceptably high in our settings.

Keywords: Vitamin D Deficiency, Recurrent Respiratory Tract Infection, Pediatric Infection, Children, Respiratory Tract Infection, Serum Vitamin D, Bangladesh