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The ongoing coronavirus disease 2019 (COVID-19) pandemic has affected hundreds of thousands of people, including infants and children. We carried out a comprehensive literature review to identify the underlying mechanisms and risk factors for severe COVID-19 in children, in comparison with the other two coronavirus outbreaks in the past, SARS and MERS. Search in the Pubmed and Scopus databases to identify publications between February 26, 2020 and June 10, 2020 identified 23 relevant papers in English. Children have so far accounted for 1.7-2% of the diagnosed cases of COVID-19. They often have milder disease than adults, and child deaths have been rare. The documented risk factors for severe disease in children are young age and underlying comorbidities, although the potentially fatal multisystem inflammatory syndrome (MIS) occurs in older children. It is unclear whether male gender and certain laboratory and imaging findings can also be considered as risk factors, due to current insufficiency of evidence. Reports on other potential factors, such as vitamin D level, responsiveness of the immune system, co-infections and genetic polymorphisms have not yet been published.

IKBKB immune deficiency is a rare but life-threatening primary immunodeficiency disorder, involving activation defects in adaptive and innate immunity. We present sixteen cases of a homozygous IKBKB mutation (c.1292dupG) in infants characterized by early-onset bacterial, viral, fungal and Mycobacterial infections. In most cases, T- and B-cells were quantitatively normal, but phenotypically naive, with severe hypogammaglobulinemia. T-cell receptor excision circles were normal, meaning newborn screening by TREC analysis would miss IKBKB cases. Although IKBKB immune deficiency does not meet traditional laboratory based definitions for SCID, this combined immune deficiency appears to be at least as profound. Urgent HSCT, performed in eight patients, remains the only known curative therapy, although only three patients are survivors. Ongoing infections after transplant remain a concern, and may be due to combinations of poor social determinants of health, secondary graft failure, and failure of HSCT to replace non-hematopoietic cells important in immune function and dependent upon IKK/NF-κB pathways.

New on-demand multiplex molecular respiratory viral diagnostics offer superior performance although can be expensive and some platforms cannot process multiple specimens simultaneously. We performed a retrospective study reviewing results of patients tested for respiratory viruses following introduction of a two-stage testing algorithm incorporating an initial screen with Sofia® immunoassay then secondary Biofire Filmarray®, and compared to a period when only Filmarray® was used. Of 2976 testing episodes, 1814 underwent initial Sofia® then follow-up FilmArray®. A diagnosis of influenza was made by Sofia® in 282 patients, and by FilmArray® in an additional 163 (median time to result 1.12 hours versus 3.46 hours, P

Objective To develop a valid research tool to measure infant respiratory illness severity using parent-reported symptoms. Study design Nose and throat swabs were collected monthly for 1 year and during respiratory illnesses for 2 years in a prospective study of term and preterm infants in the Prematurity, Respiratory Outcomes, Immune System and Microbiome study. Viral pathogens were detected using Taqman Array Cards. Parents recorded symptoms during respiratory illnesses using a Childhood Origins of Asthma (COAST) scorecard. The COAST score was validated using linear mixed effects regression modeling to evaluate associations with hospitalization and specific infections. A data-driven method was also used to compute symptom weights and derive a new score, the Infant Research Respiratory Infection Severity Score (IRRISS). Linear mixed effects regression modeling was repeated with the IRRISS illness data. Results From April 2013 to April 2017, 50 term, 40 late preterm, and 28 extremely low gestational age (

Asthma is a common and debilitating disease that has substantially increased in prevalence in Western Societies in the last 2 decades. Respiratory tract infections by respiratory syncytial virus (RSV) and rhinovirus (RV) are widely implicated as common causes of the induction and exacerbation of asthma. These infections in early life are associated with the induction of wheeze that may progress to the development of asthma. Infections may also promote airway inflammation and enhance T helper type 2 lymphocyte (Th2 cell) responses that result in exacerbations of established asthma. The mechanisms of how RSV and RV induce and exacerbate asthma are currently being elucidated by clinical studies, in vitro work with human cells and animal models of disease. This research has led to many potential therapeutic strategies and, although none are yet part of clinical practise, they show much promise for the prevention and treatment of viral disease and subsequent asthma.

Chronic obstructive pulmonary disease (COPD) exacerbations are an important cause of the considerable morbidity and mortality found in COPD. COPD exacerbations increase with increasing severity of COPD, and some patients are prone to frequent exacerbations leading to hospital admission and readmission. These frequent exacerbations may have considerable impact on quality of life and activities of daily living. Factors that increase the risk for COPD exacerbations are associated with increased airway inflammation caused by common pollutants and bacterial and/or viral infections. These inflammatory responses cause mucus hypersecretion and, thereby, airway obstruction and associated exacerbations. While chronic mucus hypersecretion is a significant risk factor for frequent and severe exacerbations, patients with chronic mucus hypersecretion have a lower rate of relapse after initial treatment for acute exacerbation. The benefit of antibiotics for treatment of COPD exacerbations is small but significant. While the mechanisms of actions are not clear, mucolytic agents reduce the number of days of disability in subjects with exacerbations. Reducing mucous cell numbers in small airways could be a useful way to reduce chronic mucus hypersecretion. Our studies suggest that programmed cell death is crucial in the resolution of metaplastic mucous cells, and understanding these mechanisms may provide novel therapies to reduce the risk of COPD exacerbations.

Type I interferons (IFN-α/β) are potent antiviral cytokines and modulators of the adaptive immune system. They are induced by viral infection or by double-stranded RNA (dsRNA), a by-product of viral replication, and lead to the production of a broad range of antiviral proteins and immunoactive cytokines. Viruses, in turn, have evolved multiple strategies to counter the IFN system which would otherwise stop virus growth early in infection. Here we discuss the current view on the balancing act between virus-induced IFN responses and the viral counterplayers.