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.