To address the novel coronavirus disease (COVID-19) pandemic, development and regulatory evaluations have been accelerated for vaccines, authorizing emergency use. To anticipate vaccine preparedness in adolescents, we studied COVID-19 vaccination awareness and willingness to vaccinate before the vaccine became available. We conducted a cross-sectional survey among 9153 (4575 boys, 50%) students with a mean age of 14.2 years old in four cities in China to collect information on demographic characteristics and their COVID-19 vaccination concerns. Multinomial logistic regression was used to analyze the influencing factors of vaccine hesitancy (“not sure”) and resistance (“do not want it”). The results showed that 2891 (31.6%) were hesitant and 765 (8.4%) were resistant to being vaccinated. Additionally, multivariable analyses showed that vaccine hesitancy and vaccine resistance were associated with living in the Beijing area (OR = 1.62; 95% CI: 1.40–1.88; OR = 1.81; 95% CI: 1.44–2.28), lack of influenza vaccination experience (OR = 1.33; 95% CI: 1.14–1.55; OR = 1.57; 95% CI: 1.25–1.98), no perceived susceptibility (OR = 1.72; 95% CI: 1.50–1.97; OR = 3.57; 95% CI: 2.86–4.46), and perceiving no cues to action (OR = 3.24; 95% CI: 2.56–4.11; OR = 27.68; 95% CI: 21.81–35.13). Postulating a highly effective vaccine (OR = 0.84; 95% CI: 0.72–0.98; OR = 0.66; 95% CI: 0.52–0.83) decreased both vaccine hesitancy and resistance. Vaccine hesitancy alone was associated with girls (OR = 1.21; 95% CI: 1.09–1.36) and was less common among students boarding at school (OR = 0.79; 95% CI: 0.68–0.92), postulating convenient vaccine access (OR = 0.84; 95% CI: 0.73–0.96), and having doctors’ recommendation (OR = 0.86; 95% CI: 0.76–0.98). In conclusion, the results of the study showed that vaccine hesitancy among students in China was associated with limited health literacy and lower risk awareness. Our findings in China suggest that educating youth regarding COVID-19 and the safety and effectiveness of immunization help reduce concerns and increase vaccine confidence and acceptance.

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Insufficient fruit and vegetable intake (FVI) and low potassium intake are associated with many non-communicable diseases, but the association with early renal damage in children is uncertain. We aimed to identify the associations of early renal damage with insufficient FVI and daily potassium intake in a general pediatric population. We conducted four waves of urine assays based on our child cohort (PROC) study from October 2018 to November 2019 in Beijing, China. We investigated FVI and other lifestyle status via questionnaire surveys and measured urinary potassium, β2-microglobulin (β2-MG), and microalbumin (MA) excretion to assess daily potassium intake and renal damage among 1914 primary school children. The prevalence of insufficient FVI (<4/d) was 48.6% (95% CI: 46.4%, 50.9%) and the estimated potassium intake at baseline was 1.63 ± 0.48 g/d. Short sleep duration, long screen time, lower estimated potassium intake, higher β2-MG and MA excretion were significantly more frequent in the insufficient FVI group. We generated linear mixed effects models and observed the bivariate associations of urinary β2-MG and MA excretion with insufficient FVI (β = 0.012, 95% CI: 0.005, 0.020; β = 0.717, 95% CI: 0.075, 1.359), and estimated potassium intake (β = −0.042, 95% CI: −0.052, −0.033; β = −1.778, 95% CI: −2.600, −0.956), respectively; after adjusting for age, sex, BMI, SBP, sleep duration, screen time and physical activity. In multivariate models, we observed that urinary β2-MG excretion increased with insufficient FVI (β = 0.011, 95% CI: 0.004, 0.018) and insufficient potassium intake (<1.5 g/d) (β = 0.031, 95% CI: 0.023, 0.038); and urinary MA excretion increased with insufficient FVI (β = 0.658, 95% CI: 0.017, 1.299) and insufficient potassium intake (β = 1.185, 95% CI: 0.492, 1.878). We visualized different quartiles of potassium intake showing different renal damage with insufficient FVI for interpretation and validation of the findings. Insufficient FVI and low potassium intake aggravate early renal damage in children and underscores that healthy lifestyles, especially adequate FVI, should be advocated.

Dehydration is common in children for physiological and behavioral reasons. The objective of this study was to assess changes in hydration status and renal impairment across school weekdays. We conducted a longitudinal study of three repeated measures of urinalysis within one week in November 2019 in a child cohort in Beijing, China. We measured urine specific gravity (USG) to determine the dehydration status, and the concentration of β2-microglobulin (β2-MG) and microalbumin (MA) to assess renal function impairment among 1885 children with a mean age of 7.7 years old. The prevalence of dehydration was 61.9%, which was significantly higher in boys (64.3%). Using chi-square tests and linear mixed-effects regression models, we documented the trends of the renal indicators’ change over time among different hydration statuses. Compared to Mondays, there were apparent increases of β2-MG concentrations on Wednesdays (β = 0.029, p < 0.001) and Fridays (β = 0.035, p < 0.001) in the dehydrated group, but not in the euhydrated group. As for the MA concentrations, only the decrease on Fridays (β = −1.822, p = 0.01) was significant in the euhydrated group. An increased trend of elevated β2-MG concentration was shown in both the euhydrated group (Z = −3.33, p < 0.001) and the dehydrated group (Z = −8.82, p < 0.001). By contrast, there was a decreased trend of elevated MA concentrations in the euhydrated group (Z = 3.59, p < 0.001) but not in the dehydrated group. A new indicator ratio, β2-MG/MA, validated the consistent trends of renal function impairment in children with dehydration. Renal impairment trends worsened as a function of school days during the week and the dehydration status aggravated renal impairment during childhood across school weekdays, especially tubular abnormalities in children.

Abnormally high lymphocyte counts are seen in persons with nonalcoholic fatty liver disease (NAFLD). Gut microbiota dysbiosis is a risk factor for NAFLD. We assessed the gut microbiota of 63 healthy children and 63 children with NAFLD using 16S rRNA gene and metagenomic sequencing to explore the relationships. Compared with healthy children (HC group), the Bacteroidetes, Verrucomicrobia, and Akkermansia were less abundant, while the Actinobacteria were more abundant in children with NAFLD (FLD group). To understand the effect of lymphocytes on the gut microbiota of children with NAFLD, we compared the microbiota of 41 children with NAFLD and high numbers of lymphocytes (FLD_HL group) and 22 children with NAFLD and low numbers of lymphocytes (FLD_LL group). The abundances of Bacteroidetes, Verrucobacterium, and Akkermansia increased and Actinobacteria decreased in the FLD_LL group compared to the FLD_HL group. Akkermansia was negatively correlated with lymphocyte count. NAFLD may disturb the gut microbiota in children through reducing the abundance of Akkermansia and increasing the abundance of proinflammatory bacteria, such as Escherichia-Shigella. Conclusions: High lymphocyte counts are associated with disturbances of gut microbiota and emergence of opportunistic pathogens in children with NAFLD.