Serum 25-Hydroxy Vitamin D Levels in Children with Acute Respiratory Infections Caused by Respiratory Virus or Atypical Pathogen Infection

We aimed to clarify the involvement of vitamin D status in virus or atypical pathogens infection in children with acute respiratory infections (ARIs). In this retrospective study, 295 patients with ARIs were attacked by a respiratory virus or a single atypical pathogen; 17 patients with ARIs induced by two pathogens, and 636 healthy children were included. Serum 25(OH)D levels of all children were measured. Oropharyngeal samples of the patients for viruses or atypical pathogens were studied by polymerase chain reaction (PCR) or reverse transcription-polymerase chain reaction (RT-PCR). In our studies, 58.98% of the 295 single-infected subjects and 76.47% of the 17 co-infected subjects had 25(OH)D levels below the recommended 50.0 nmol/L; the mean 25(OH)D levels were 48.48 ± 19.91 nmol/L and 44.12 ± 12.78 nmol/L. Low serum 25(OH)D levels were remarkable in patients with one of seven viruses or atypical pathogens infected. These results were significantly different from those in the healthy group. There were no significant differences in 25(OH)D levels between single infection and co-infection groups. There were no differences in severity among means of 25(OH)D levels. Female or >6-year-old children patients with low serum 25(OH)D levels were more vulnerable to pathogenic respiratory pathogens. However, serum 25(OH)D levels may be related to the recovery of ARIs. These findings provide additional evidence for the development of strategies to prevent ARIs in children.