Impact of the COVID-19 Pandemic on Growth, Nutrition, and Immune Function in Infants and Toddlers

OBJECTIVE: To evaluate the impact of the COVID-19 pandemic on physical growth, nutritional intake, and immune function in children aged 12-24 months. DESIGN: A cross-sectional analysis was conducted utilizing data from the National Health and Nutrition Examination Survey (NHANES). Pre-pandemic (2017-2018) and pandemic (2021-2023) cohorts were compared. SETTING: Nationally representative data from the United States. PARTICIPANTS: Children aged 12-24 months (pre-pandemic: n = 3,904,863; pandemic: n = 3,496,904). RESULTS: No significant differences were observed in physical growth (weight, length, BMI) or macronutrient intake between cohorts. Pandemic-born children had lower vitamin A (437.0 vs. 540.0 mcg/day, p = 0.006) and B12 (2.7 vs. 3.4 mcg/day, p = 0.009) intake but higher vitamin C intake (87.0 vs. 62.8 mg/day, p < 0.001). Inflammatory markers (NLR, PLR, SII) showed minor age- and sex-specific variations but remained within normal ranges. Environmental toxin exposure (cadmium, mercury) was significantly reduced during the pandemic. CONCLUSIONS: The COVID-19 pandemic did not substantially alter growth, nutrition, or immune function in infants and toddlers, though micronutrient intakes and toxin exposure shifted. Long-term monitoring is warranted.