Effect of Pandemic-Related Confinement on Vitamin D Status Among Children Aged 0–6 Years in Guangzhou, China: A Cross-Sectional Study

PURPOSE: Pandemic-related confinement helps to contain the transmission of the novel coronavirus disease (COVID-19) but restricts children’s exposure to sunlight, thereby possibly affecting their 25-hydroxyvitamin D [25(OH)D] levels. This study aimed to examine the effect of COVID-19 measures on 25(OH)D levels in children. PATIENTS AND METHODS: This study included children who underwent health checks between March 1 and June 30, 2020, and those over the equivalent period during 2017–2019 (N = 3600). Children’s 25(OH)D levels and the proportion of children with vitamin D deficiency were compared between different observation periods. RESULTS: The mean serum 25(OH)D level was 84 ± 25nmol/L. The overall proportion of children with vitamin D deficiency (25(OH)D level <50 nmol/L) was 4.6%. Home confinement led to an increase in the proportion of children aged 3–6 years with vitamin D deficiency during March 1–June 30, 2020 compared with the same months in previous years, and the most noticeable increase was found in March 2020. In children aged 3–6 years, 25(OH)D levels were lower in 2020 (65 ± 17nmol/L) than during 2017–2019, and the proportion of those with vitamin D deficiency was higher in 2020 (19.0%) than in previous years. Among children aged 0.5–1 and 1–3 years, 25(OH)D levels were higher (97 ± 25 nmol/L, 91 ± 27 nmol/L), while the proportion of children with vitamin D deficiency was lower in 2020 (2.3%, 3.0%) than during 2017–2019. CONCLUSION: The 25(OH)D levels tended to decrease gradually with increasing age. Reduced sunlight exposure during confinement is associated with lower 25(OH)D levels among children aged 3–6 years. Therefore, vitamin D supplementation for children aged >3 years is recommended.