Objective To provide a comprehensive and systematic analysis of demographic characteristics, clinical symptoms, laboratory findings and imaging features of coronavirus disease 2019 (COVID‐19) in pediatric patients. Methods A meta‐analysis was carried out to identify studies on COVID‐19 from December 25, 2019 to April 30, 2020. Results A total of 48 studies with 5829 pediatric patients were included. Children at all ages were at risk for COVID‐19. The main illness classification ranged as: 20% (95% CI: 14 to 26%, I 2 =91.4%) asymptomatic, 33% (95% CI: 23 to 43%, I 2 =95.6%) mild and 51% (95% CI: 42 to 61%, I 2 =93.4%) moderate. The typical clinical manifestations were fever 51% (95% CI: 45 to 57%, I 2 =78.9%) and cough 41% (95% CI: 35 to 47%, I 2 =81.0%). The common laboratory findings were normal white blood cell 69% (95% CI: 64 to 75%, I 2 =58.5%), lymphopenia 16% (95% CI: 11 to 21%, I 2 =76.9%) and elevated creatine‐kinase MB (CK‐MB) 37% (95% CI: 25 to 48%, I 2 =59.0%). The frequent imaging features were normal images 41% (95% CI: 30 to 52%, I 2 =93.4%) and ground‐glass opacity 36% (95% CI: 25 to 47%, I 2 =92.9%). Among children under 1‐year old, critical cases account for 14% (95% CI: 13 to 34%, I 2 =37.3%) that should be of concern. In addition, vomiting occurred in 33% (95% CI: 18 to 67%, I 2 =0.0%) cases that may also need attention. Conclusions Pediatric patients with COVID‐19 may experience milder illness with atypical clinical manifestations and rare lymphopenia. High incidence of critical illness and vomiting symptoms reward attention in children under 1‐year old. This article is protected by copyright. All rights reserved.

Coronavirus Disease 2019 (COVID‐19) is a newly emerging infectious disease caused by a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). After its first occurrence in Wuhan of China from December 2019, COVID‐19 rapidly spread around the world. According to the World Health Organization statement on 13 March 2020, there had been over 132 500 confirmed cases globally. Nevertheless, the case reports of children are rare, which results in the lack of evidence for preventing and controlling of children's infection. Here, we report three cases of SARS‐CoV‐2 infected children diagnosed from 3 February to 17 February 2020 in Tianjin, China. All of these three cases experienced mild illness and recovered soon after the treatment, with the nucleic acid of throat swab turning negative within 14, 11, and 7 days after diagnosis, respectively. However, after been discharged, all three cases were tested SARS‐CoV‐2 positive in the stool samples within 10 days, in spite of their remained negative nucleic acid in throat swab specimens. Therefore, it is necessary to be aware of the possibility of fecal‐oral transmission of SARS‐CoV‐2 infection, especially for children cases.

Chronic inflammation in adipose tissue plays a key role in obesity-induced insulin resistance. However, the mechanisms underlying obesity-induced inflammation remain elusive. Here we show that obesity promotes mtDNA release into the cytosol, where it triggers inflammatory responses by activating the DNA-sensing cGAS-cGAMP-STING pathway. Fat-specific knockout of disulfide-bond A oxidoreductase-like protein (DsbA-L), a chaperone-like protein originally identified in the mitochondrial matrix, impaired mitochondrial function and promoted mtDNA release, leading to activation of the cGAS-cGAMP-STING pathway and inflammatory responses. Conversely, fat-specific overexpression of DsbA-L protected mice against high-fat diet-induced activation of the cGAS-cGAMP-STING pathway and inflammation. Taken together, we identify DsbA-L as a key molecule that maintains mitochondrial integrity. DsbA-L deficiency promotes inflammation and insulin resistance by activating the cGAS-cGAMP-STING pathway. Our study also reveals that, in addition to its well-characterized roles in innate immune surveillance, the cGAS-cGAMP-STING pathway plays an important role in mediating obesity-induced metabolic dysfunction.

Metformin is the most commonly prescribed drug for type 2 diabetes mellitus. In recent years, in addition to glucose lowering, several studies have presented evidence suggesting some potential role for metformin, such as antitumor effect, antiaging effect, cardiovascular protective effect, neuroprotective effect or an optional treatment for polycystic ovary syndrome. This paper will critically review the role of metformin to provide reference for doctors and researchers.