As 2019-nCoV vaccine is widely used in the adult population, children and adolescents have gradually become an important susceptible population to 2019-nCoV due to their low coverage of the vaccine and high contact degree. Understanding the characteristics of 2019-nCoV infection in minors is vital. This paper summarized the progress in the research of 2019-nCoV in minors by using the data from the retrieval of recently published literature. Furthermore, the key characteristics of 2019-nCoV infection in minors, including the susceptibility, transmissibility, prognosis and immune response were analyzed and the progress in child and adolescent vaccine development was introduced.

Objective To investigate the dose of radiation in children under going X-ray-guided air enema reduction, and to provide a basis for reducing the risk of radiation injury in pediatric patients. Methods Data were collected from children with intussusception who were treated with air enema. The experimental conditions of high, medium, and low doses of three age groups were analyzed. Phantoms were used to simulate the operation, and the radiation dose was measured using a thermoluminescence system. Results In children with intussusception, the success rate of air enema under the guidance of X-ray was 88% (including secondary intussusception), with anearly re-intussusception rate of 8%. The effective dose of treatment ranged from 0.57 to 12.33 mSv, and the tissues and organs with high absorbed dose were mainly in the chest and abdomen. Conclusion Children in different groups are exposed to significantly differentand relatively high doses. The operators are recommended to use ultrasonic guidance. With X-ray guidance, the exposure time should be minimized and protective equipment for children should be used.

ObjectiveTo explore the association between short-term exposure to atmospheric fine particulate matter （PM_2.5） and ozone （O₃） and systemic inflammatory indicators in patients with pneumonia， and to identify the susceptible populations. MethodsFrom September 2018 to April 2020， data of 1 480 patients admitted for pneumonia was collected from a tertiary hospital in Taiyuan City. Generalized additive models （GAMs） were used to explore the associations between PM_2.5 and O₃ exposure and inflammatory indicators of patients with pneumonia； and to explore the susceptibility factors and susceptible populations to PM_2.5 and O₃ exposures through stratified analyses. ResultsThe short-term exposure to PM_2.5 was associated with changes in peripheral blood C-reation protein （CRP）， erythrocyte sedimentation （ESR）， easinophil （EOS）， neutrophil （NEU） and neutrophil-lymphocyte ratio （NLR） in patients with pneumonia， and there were different degrees of hysteresis effects， with the effect values reaching a maximum at lag03， lag03， lag0， lag03， lag03， respectively， which were 4.13% （95%CI： 0.43%‒7.84%）， 3.10% （95%CI： 0.24%‒5.97%）， 5.27% （95%CI： 3.12%‒7.42%）， 1.85% （95%CI： 0.36%‒3.34%）， and 2.53% （95%CI： 0.53%‒4.74%） for every 10 μg·m^-3 of PM_2.5. The changes in O₃ concentration were associated with the elevation of peripheral blood PCT and ESR in patients with pneumonia， and their effect values all reached the maximum at lag01 d， every 1 μg·m^-3 of O₃ elevation increased by 0.38% （95%CI： 0.04%‒0.73%） and 0.47% （95%CI： 0.19%‒0.76%）， respectively. Stratified analyses showed that the associations of PM_2.5 with peripheral blood CRP， ESR， NEU， and NLR in pneumonia patients were more significant in males， the elderly， and those with onset in the cold season； the associations of O₃ with peripheral blood PCT and ESR in pneumonia patients were more significant in the elderly and those with onset in the warm season， and the peripheral blood CRP and PCT in female patients with pneumonia were more susceptible to the changes of O₃. ConclusionShort-term exposure to atmospheric PM_2.5 and O₃ are positively associated with changes in inflammatory indicators in patients with pneumonia， and the effects of PM_2.5 on patients with pneumonia are more extensive than those of O₃， with a longer lag effect. In addition， elderly patients with pneumonia are more sensitive to air pollution， male patients with pneumonia are more sensitive to PM_2.5， and female patients with pneumonia are more sensitive to O₃. Cold and warm seasons can exacerbate the effects of PM_2.5 and O₃ on inflammatory indicators in patients with pneumonia， respectively， and the patients must be protected well.