# Exploring the Association of Vitamin D and VDR Polymorphisms with Disease Severity in COVID-19 and Influenza

## TL;DR

This study explores how vitamin D levels and genetic variations in the vitamin D receptor relate to the severity of respiratory infections like COVID-19 and influenza.

## Contribution

The study provides new insights into the potential role of vitamin D in modulating disease severity in respiratory infections.

## Key findings

- Vitamin D levels were significantly lower in severe cases of COVID-19 and influenza compared to moderate cases.
- No significant association was found between VDR polymorphisms and disease severity or vitamin D levels.
- Severe respiratory infection cases showed higher inflammatory markers and lower lymphocyte counts.

## Abstract

Background: Respiratory viral infections such as COVID-19 and influenza represent significant public health threats, especially in vulnerable populations. Vitamin D has been promoted as an immunomodulatory agent, with previous studies suggesting an association between vitamin D levels and disease severity in respiratory infections. Additionally, genetic variations in the vitamin D receptor (VDR) may influence immune responses. Methods: This study investigates the relationship between vitamin D levels, VDR polymorphisms (rs1544410, rs731236, and rs7975232), and clinical severity in hospitalized patients with COVID-19 and influenza during the 2023–2024 winter season. Results: A total of 71 patients were included in this cross-sectional study. Vitamin D levels were significantly lower in severe COVID-19 cases (8.08 ng/mL, IQR: 4.79–15.7) compared to moderate forms (32.6 ng/mL, IQR: 13.0–38.6), as well as severe influenza cases (25.6 ng/mL, IQR: 18.9–34.5). Additionally, severe COVID-19 patients exhibited higher inflammatory markers (CRP, neutrophil count) and lower lymphocyte counts. However, no significant association was found between VDR polymorphisms and disease severity or vitamin D levels. Conclusions: These findings highlight the potential role of vitamin D in modulating disease severity in respiratory viral infections, while the influence of genetic polymorphisms remains uncertain. Further research is needed to determine whether vitamin D supplementation could improve clinical outcomes in these infections.