Coronavirus disease 2019 and the gut-lung axis.

Gastrointestinal and respiratory tract diseases often occur together. There are many overlapping pathologies, leading to the concept of the 'gut-lung axis' in which stimulation on one side triggers a response on the other side. This axis appears to be implicated in infections involving severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which has triggered the global coronavirus disease 2019 (COVID-19) pandemic, in which respiratory symptoms of fever, cough and dyspnoea often occur together with gastrointestinal symptoms such as nausea, vomiting, abdominal pain and diarrhoea. Besides the gut-lung axis, it should be noted that the gut participates in numerous axes which may affect lung function, and consequently the severity of COVID-19, through several pathways. This article focuses on the latest evidence and the mechanisms that drive the operation of the gut-lung axis, and discusses the interaction between the gut-lung axis and its possible involvement in COVID-19 from the perspective of microbiota, microbiota metabolites, microbial dysbiosis, common mucosal immunity and angiotensin-converting enzyme II, raising hypotheses and providing methods to guide future research on this new disease and its treatments.

Bilateral associations between sleep duration and depressive symptoms among Chinese adolescents before and during the COVID-19 pandemic.

Depression is one of the most prevalent psychiatric disorders and the leading cause of disability among adolescents, with sleep duration as its vital influential factor. Adolescents might be mentally sensitive to the stress caused by the COVID-19 pandemic. Yet, the alteration of adolescents' sleep duration, depression, and their associations within the context of the COVID-19 pandemic have not been well documented. We conducted a longitudinal study, recruiting 2496 adolescents from 3 junior high schools to examine the alteration of their sleep duration and depressive symptoms before and during the pandemic, and to explore their potential association(s). Data were collected before (December 2019) and during the pandemic (July 2020). Paired samples t-test revealed a significant decrease in sleep duration and a significant increase in depressive symptoms during the COVID-19 pandemic. Higher grades, COVID-19 infection history, higher CES-DC score, and the COVID-19 pandemic itself might contribute to decreased sleep duration, while longer exercise duration during the pandemic might be a protective factor. According to the cross-lagged analysis, the existence of depressive symptoms before the pandemic was significantly associated with a shorter sleep duration during the pandemic (ß = -0.106, p < 0.001). Previously shortened sleep duration was significantly associated with a greater likelihood of depressive symptoms during the pandemic (ß = -0.082, p < 0.001). Our findings revealed that the COVID-19 pandemic has a negative influence on adolescents' mental health and sleep. Mental preparedness should be highlighted to mitigate the psychosocial influences of any possible public emergencies in the future. Sleep duration represents a viable home-based intervention for depressive symptoms.

Effect of COVID-19 on childhood Mycoplasma pneumoniae infection in Chengdu, China.

BACKGROUND: Following the outbreak of the COVID-19 pandemic, a change in the incidence and transmission of respiratory pathogens was observed. Here, we retrospectively analyzed the impact of COVID-19 on the epidemiologic characteristics of Mycoplasma pneumoniae infection among children in Chengdu, one of the largest cities of western China. METHOD: M. pneumoniae infection was diagnosed in 33,345 pediatric patients with respiratory symptoms at the Chengdu Women's & Children's Central Hospital between January 2017 and December 2020, based on a serum antibody titer of ≥1:160 measured by the passive agglutination assay. Differences in infection rates were examined by sex, age, and temporal distribution. RESULTS: Two epidemic outbreaks occurred between October-December 2017 and April-December 2019, and two infection peaks were detected in the second and fourth quarters of 2017, 2018, and 2019. Due to the public health response to COVID-19, the number of positive M. pneumoniae cases significantly decreased in the second quarter of 2020. The number of M. pneumoniae infection among children aged 3-6 years was higher than that in other age groups. CONCLUSIONS: Preschool children are more susceptible to M. pneumoniae infection and close contact appears to be the predominant factor favoring pathogen transmission. The public health response to COVID-19 can effectively control the transmission of M. pneumoniae.