Objectives To outline which infectious diseases in the pre-covid-19 era persist in children and adolescents in China and to describe recent trends and variations by age, sex, season, and province. Design National surveillance studies, 2008-17. Setting 31 provinces in mainland China. Participants 4 959 790 Chinese students aged 6 to 22 years with a diagnosis of any of 44 notifiable infectious diseases. The diseases were categorised into seven groups: quarantinable; vaccine preventable; gastrointestinal and enteroviral; vectorborne; zoonotic; bacterial; and sexually transmitted and bloodborne. Main outcome measures Diagnosis of, and deaths from, 44 notifiable infectious diseases. Results From 2008 to 2017, 44 notifiable infectious diseases were diagnosed in 4 959 790 participants (3 045 905 males, 1 913 885 females) and there were 2532 deaths (1663 males, 869 females). The leading causes of death among infectious diseases shifted from rabies and tuberculosis to HIV/AIDS, particularly in males. Mortality from infectious diseases decreased steadily from 0.21 per 100 000 population in 2008 to 0.07 per 100 000 in 2017. Quarantinable conditions with high mortality have effectively disappeared. The incidence of notifiable infectious diseases in children and adolescents decreased from 280 per 100 000 in 2008 to 162 per 100 000 in 2015, but rose again to 242 per 100 000 in 2017, largely related to mumps and seasonal influenza. Excluding mumps and influenza, the incidence of vaccine preventable diseases fell from 96 per 100 000 in 2008 to 7 per 100 000 in 2017. The incidence of gastrointestinal and enterovirus diseases remained constant, but typhoid, paratyphoid, and dysentery continued to decline. Vectorborne diseases all declined, with a particularly noticeable reduction in malaria. Zoonotic infections remained at low incidence, but there were still unpredictable outbreaks, such as pandemic A/H1N1 2009 influenza. Tuberculosis remained the most common bacterial infection, although cases of scarlet fever doubled between 2008 and 2017. Sexually transmitted diseases and bloodborne infections increased significantly, particularly from 2011 to 2017, among which HIV/AIDS increased fivefold, particularly in males. Difference was noticeable between regions, with children and adolescents in western China continuing to carry a disproportionate burden from infectious diseases. Conclusions China’s success in infectious disease control in the pre-covid-19 era was notable, with deaths due to infectious diseases in children and adolescents aged 6-22 years becoming rare. Many challenges remain around reducing regional inequalities, scaling-up of vaccination, prevention of further escalation of HIV/AIDS, renewed efforts for persisting diseases, and undertaking early and effective response to highly transmissible seasonal and unpredictable diseases such as that caused by the novel SARS-CoV-2 virus.

We sought to develop and validate a national blood pressure (BP) reference based on age, sex, and height for Chinese children. Data were obtained on 197 430 children aged 7 to 17 who participated in the Chinese National Survey on Students’ Constitution and Health in 2010. BP percentiles were estimated and fitted using the lambda, mu, and sigma method and then compared with a US reference and China existing reference. In an external independent validation sample of 59 653 children aged 7 to 18 from 7 Chinese provinces in 2013, the prevalence of elevated BP was compared applying the 3 references. BP values were similar for boys and girls at the younger ages (7–13 years) and lower height percentiles, whereas higher at the older ages (14–17 years) for boys than girls. At medial height in boys and girls aged 7 to 13, the 50th, 90th, 95th, and 99th percentiles of BP for the new national reference were consistent with US reference and lower than current Chinese reference. In the independent sample, elevated BP prevalence, based on the new national reference, ranged from 7.8% to 18.5% among children aged 7 to 17, which was higher than the US reference values (4.3%–14.5%) and lower than the current Chinese reference (12.9%–25.5%) in each age group. The new national BP reference for Chinese children based on age, sex, and height from large-scale and nationally representative data seems to improve the ability for identifying Chinese hypertensive children and for stratifying them with regard to cardiovascular risk.

The current study aimed to assess the secular trends in overweight and obesity status and high blood pressure (HBP) in Chinese children and adolescents for 2 decades. Data on 943 128 participants aged 7 to 17 years were obtained from the Chinese National Survey on Students’ Constitution and Health from 1995 to 2014. The population attributable risk of overweight status for HBP was calculated. The prevalence of overweight increased from 4.3% in 1995 to 18.4% in 2014, whereas HBP prevalence fluctuated in the range of 4.4% to 6.4% during the same time period, the lowest in 2005. Within each survey year, blood pressure levels and HBP prevalence increased with higher body mass index. Notably, the population attributable risk of HBP because of being overweight steadily increased from 6.3% in 1995 to 19.2% in 2014. The same trends of linear growth for obesity, fluctuating blood pressure, and its sustained increasing population attributable risk for overweight also occurred among the domestic 29 provinces. Despite dramatic increases in overweight prevalence among Chinese children from 1995 to 2014, the HBP prevalence remained relatively stable, suggesting that other independent factors are affecting HBP trends to a greater extent. Yet, over time, the magnitude of the impact of being overweight or obese on HBP increased sharply, predicting looming heavy burden of HBP. Reductions in overweight status may aid in preventing HBP so as to prevent coronary risk in adulthood.

Gene polymorphisms associated so far with body mass index (BMI) can explain only 1.18–1.45% of observed variation in BMI. Recent studies suggest that epigenetic modifications, especially DNA methylation, could contribute to explain part of the missing heritability, and two epigenetic genome-wide analysis studies (EWAS) have reported that Hypoxia Inducible Factor 3 Alpha Subunit (HIF3A) methylation was associated with BMI or BMI change. We therefore assessed whether the HIF3A methylation is associated with obesity and other obesity-related phenotypes in Chinese children. The subjects included 110 severe obese cases aged 7–17y and 110 normal-weight controls matched by age and gender for measurement of blood DNA methylation levels at the HIF3A gene locus using the Sequenom’s MassARRAY system. We observed significantly higher methylation levels in obese children than in controls at positions 46801642 and 46801699 in HIF3A gene (P<0.05), and found positive associations between methylation and alanine aminotransferase (ALT) levels adjusted by gender, age and BMI at the position 46801699 (r = 0.226, P = 0.007). These results suggest that HIF3A DNA methylation is associated with childhood obesity, and has a BMI-independent association with ALT. The results provide evidence for identifying epigenetic factors of elivated ALT and may be useful for risk assessment and personalized medicine of liver diseases such as non-alcoholic fatty liver disease (NAFLD).