Impact of home confinement due to the COVID-19 outbreak on vitamin D levels and trends among children with pneumonia aged 1-35 months.

Vitamin D plays a vital role in immunity and is related to susceptibility and the severity of pneumonia. The home confinement caused by the novel coronavirus disease (COVID-19) decreased sunlight exposure derived from outdoor activities in children, thereby possibly exerting an influence on 25-hydroxyvitamin D [25(OH)D] levels. The aim of this study is to quantify vitamin D level changes and trends among infants and toddlers with community-acquired pneumonia (CAP) during and post the home confinement period. This study included children who were hospitalized in the respiratory department of the Children's Hospital of Chongqing Medical University with CAP between February 1 and July 31 from 2020 to 2022 ( = 397). We used propensity score matching to control the confounding bias. The levels and trends of the children's serum 25(OH)D concentrations overall and by age groups were compared between the different periods. The serum 25(OH)D concentration during the home confinement period was lower ( < 0.05) but was still at the vitamin D sufficiency level. There was a gradual decrease in the 25(OH)D concentrations in the subsequent several months after the beginning of home confinement, and the recovery time was delayed. When analyzed by age group, the serum 25(OH)D concentration of the toddler group changed more significantly than that of the infant group between the different periods. The insufficiency of sunlight exposure caused by home confinement resulted in a slight and gradual decrease in vitamin D levels among children with CAP. In addition, the impact was more significant for toddlers.