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Aim: This study aimed to identify the epidemiological characteristics and transmission dynamics of paediatric cases.Methods: Information on 1369 paediatric cases with COVID-19 from 8 December 2019 to 7 March 2020 in Hubei province was extracted from the National Infectious Disease Surveillance System. The analysis included epidemic curves, temporal-spatial distribution, clinical classification and interval times between onset and diagnosis.Results: Among 1369 paediatric cases, the median age was 9 years and 58.2% of them were males. The proportion of severe and critical cases in children was lower than that in adults and the proportion of asymptomatic cases in children was five times greater than for adult cases. The first paediatric case was reported on 2 January 2020, and the daily number of new paediatric cases remained high from 1 February through to 22 February. The epidemiological curve of paediatric cases lagged behind that of adults by 19 days, and the first spike of the epidemic curve in senior high school students occurred 1 week earlier than in other paediatric groups. The proportion of clustered cases among children was about twice that for adults. The median of the interval in paediatric cases between onset and diagnosis, isolation and notification were 3, 0 and 3 days, respectively, and all of those were significantly shorter than in adults.Conclusions: The epidemic curve of child cases lagged behind that of adult cases by 19 days, and the major form of transmission observed was in clusters. [ABSTRACT FROM AUTHOR]

PM 2.5 exposure leads to lung function alteration. The potential pathway underlying above association, especially the role of DNA methylation is unclear. The objectives of this study are to evaluate the associations of personal PM 2.5 concentrations with DNA methylation at the epigenome-wide level, and investigate how PM 2.5 -related DNA methylation affects lung function. A total of 402 observations of non-smokers were selected from the Wuhan-Zhuhai cohort. PM 2.5 exposure was estimated through a model established in the same population. Blood DNA methylation levels were determined through Illumina Infinium MethylationEPIC BeadChips. Lung function was tested through spirometry on the day of blood sampling. The associations of PM 2.5 exposure with DNA methylation and DNA methylation with lung function were determined through linear mixed models. Ten PM 2.5 -related CpG sites (mapped to 7 different genes) were observed with false discovery rate <0.05. Methylation levels of cg24821877, cg24862131, cg23530876, cg11149743 and cg10781276 were positively associated with PM 2.5 concentrations. While methylation levels of cg10314909, cg08968107, cg18362281, cg24663971 and cg17834632 were negatively associated with PM 2.5 concentrations. The top CpG was cg24663971 (P = 1.51✕10 -9 ). Among the above 10 sites, significantly positive associations of methylation levels of cg24663971 with FVC%pred and FEV 1 %pred, and cg10314909 with FVC, FVC%pred, and FEV 1 %pred were observed. Age had modification effect on the associations between cg24663971 methylation and FVC%pred, and the associations were more obvious among participants with age ≥58 years. In conclusion, PM 2.5 exposure was associated with DNA methylation, and PM 2.5 -related DNA methylation was associated with lung function among Wuhan urban non-smokers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Short-term effects of fine particulate matter (PM 2.5 ) exposure on lung function have been reported. However, few studies have assessed PM 2.5 exposure on the personal level, and the mechanism underlying the effects of PM 2.5 exposure on lung function remains less clear., Objectives: To evaluate the association between personal PM 2.5 exposure and lung function alteration in general population and to explore the roles of systematic inflammation and oxidative damage in this association., Methods: A total of 7685 lung function tests were completed among 4697 urban adults in Wuhan, China. Plasma C-reactive protein (CRP), urinary 8-iso-prostaglandin-F 2α (8-iso-PGF 2α ) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were measured. Personal PM 2.5 exposure levels were estimated using an estimation model from the actual measurements of individual PM 2.5 levels in 191 participants. Mixed linear models were used to evaluate the association between personal PM 2.5 exposure and lung function. Mediation analyses were conducted to investigate the roles of CRP, 8-iso-PGF 2α and 8-OHdG in above associations., Results: After adjusting for confounders, each 10 μg/m 3 increase in the previous-day personal PM 2.5 exposure was associated with 2.94 mL, 2.02 mL and 16.14 mL/s decreases in forced vital capacity (FVC), forced expiration volume in 1 s (FEV 1 ) and peak expiratory flow, respectively. The associations were more obvious among never smokers compared with current smokers. Cumulative 7-day exposure to PM 2.5 led to the strongest adverse effects on lung function. Among never smokers with high PM 2.5 exposure levels, a positive relationship was observed between personal PM 2.5 level and urinary 8-iso-PGF 2α , and 8-iso-PGF 2α meditated 4.69% and 12.30% of the association between the 7-day moving PM 2.5 concentration and FVC and FEV 1 , respectively. We did not observe a significant positive association between PM 2.5 exposure and plasma CRP or urinary 8-OHdG., Conclusion: Short-term personal exposure to PM 2.5 is associated with reduced pulmonary ventilation function. Urinary 8-iso-PGF 2α partly mediates these associations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)