Respiratory syncytial virus (RSV) infection in the first year of life has been linked with an increased risk for asthma. Some propose that RSV-induced inflammation leads to lasting airway changes, while others contend that RSV bronchiolitis is a marker for underlying predisposition. Social distancing adopted during the COVID-19 pandemic has led to a dramatic reduction in RSV activity, providing an unexpected opportunity to investigate this debate.

To compare the incidence of asthma-related healthcare-utilization (HCU) in 1-3 years of age between children born in March-June 2020 (l-RSV) and children born during the same months in the years 2014-2017 (H-RSV).

This retrospective study utilized nationwide healthcare database records from Clalit-Healthcare-Services, the largest healthcare organization in Israel. The study analyzed asthma-related HCU, using multivariate logistic regression and Bayesian analyses.

172,463 children were included in the study: 32,927 in the l-RSV group versus 139,536 in the H-RSV group. The l-RSV cohort showed insignificant changes and increased rates of asthma-related HCU between 1 and 3 years of age in some asthma surrogates, compared to the H-RSV group.

Reduction in RSV exposure during the first year of life did not correlate with a decrease in asthma-related HCU. This may imply that RSV infection in infancy functions as an indicator of underlying predisposition rather than a direct cause of asthma.

Background: Human milk is recognized as an ideal food for newborns and infants owing to the presence of various nutritive factors, including healthy bacteria. Aim/Objective: This review aimed to understand the effects of human milk microbiota in both the prevention of disease and the health of infants. Methods: Data were obtained from PubMed, Scopus, Web of Science, clinical trial registries, Dergipark, and Türk Atıf Dizini up to February 2023 without language restrictions. Results: It is considered that the first human milk microbiota ingested by the newborn creates the initial microbiome of the gut system, which in turn influences the development and maturation of immunity. Bacteria present in human milk modulate the anti-inflammatory response by releasing certain cytokines, protecting the newborn against certain infections. Therefore, certain bacterial strains isolated from human milk could serve as potential probiotics for various therapeutic applications. Conclusions: In this review, the origin and significance of human milk bacteria have been highlighted along with certain factors influencing the composition of human milk microbiota. In addition, it also summarizes the health benefits of human milk as a protective agent against certain diseases and ailments.

The gut microbiome has been shown to play a critical role in maintaining a healthy state. Dysbiosis of the gut microbiome is involved in modulating disease severity and potentially contributes to long-term outcomes in adults with COVID-19. Due to children having a significantly lower risk of severe illness and limited sample availability, much less is known about the role of the gut microbiome in children with COVID-19. It is well recognized that the developing gut microbiome of children differs from that of adults, but it is unclear if this difference contributes to the different clinical presentations and complications. In this review, we discuss the current knowledge of the gut microbiome in children with COVID-19, with gut microbiome dysbiosis being found in pediatric COVID-19 but specific taxa change often differing from those described in adults. Additionally, we discuss possible mechanisms of how the gut microbiome may mediate the presentation and complications of COVID-19 in children and the potential role for microbial therapeutics.

Coronavirus disease 2019 (COVID-19) is an infectious disease with a wide range of respiratory and extrapulmonary symptoms, as well as gastrointestinal symptoms. Despite recent research linking gut microbiota to infectious diseases like influenza, minimal information is known about the gut microbiota's function in COVID-19 pathogenesis. Studies suggest that dysbiosis of the gut microbiota and gut barrier dysfunction may play a role in COVID-19 pathogenesis by disrupting host immune homeostasis. Regardless of whether patients had taken medication or disease severity, the gut microbiota composition was significantly altered in COVID-19 patients compared to non-COVID-19 individuals. Several gut commensals with recognized immunomodulatory potential, such as Faecalibacterium prausnitzii, Eubacterium rectale, and bifidobacteria, were underrepresented in patients and remained low in samples taken several weeks after disease resolution. Furthermore, even with disease resolution, dysbiosis in the gut microbiota may contribute to chronic symptoms, underscoring the need to learn more about how gut microbes play a role in inflammation and COVID-19.

Gastrointestinal (GI) involvement has been reported in approximately 50% of patients with coronavirus disease 2019 (COVID-19), which is due to the pathogenic role of inflammation and the intestinal function of the angiotensin-converting enzyme 2 and its receptor. Accumulating adult data has pointed out that gut dysbiosis might occur in these patients with a potential impact on the severity of the disease, however the role of gut microbiota in susceptibility and severity of COVID-19 disease in children is still poorly known. During the last decades, the crosstalk between gut and lung has been largely recognized resulting in the concept of "gut-lung axis" as a central player in modulating the development of several diseases. Both organs are involved in the common mucosal immune system (including bronchus-associated and gut-associated lymphoid tissues) and their homeostasis is crucial for human health. In this framework, it has been found that the role of GI dysbiosis is affecting the homeostasis of the gut-liver axis. Of note, a gut microbiome imbalance has been linked to COVID-19 severity in adult subjects, but it remains to be clarified. Based on the increased risk of inflammatory diseases in children with COVID-19, the potential correlation between gut microbiota dysfunction and COVID-19 needs to be studied in this population. We aimed to summarize the most recent evidence on this striking aspect of COVID-19 in childhood.