Recent evidence highlights additional modifiers of vitamin D-mediated immunity, including maternal vitamin D status, vitamin D receptor (VDR) genetic polymorphisms, early-life immune programming, and respiratory microbiome interactions, which may explain variability in clinical outcomes across populations and developmental stages.<h4>Conclusion</h4>Overall, this review provides a comprehensive framework linking vitamin D biology with immune system development in children and their risk of pneumonia. Here, VDR is linked to pneumonia.