Background: The clinical impact of severe coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in immunocompromised patients has not been systematically evaluated. Methods: We reviewed current literature reporting on COVID-19 in cancer (CA), hematopoietic cell (HCT), and solid organ transplant (SOT) patients and compared their clinical data and outcomes to the general population. For adult CA, HCT and SOT patients, an extensive search strategy retrieved all articles published until July 20, 2020 by combining the terms coronavirus, coronavirus infection, COVID-19 , and SARS-CoV-2 in PubMed, Cochrane, and Web of Science, and following the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. For the pediatric CA cohort, a global COVID-19 registry was used. For the general population cohort, a large meta-analysis was used to compare pooled prevalence estimates, and two large meta-analyses were utilized to serve as pooled comparators for hospitalized COVID-19 patients. Findings: Compared to the general population, adult CA and SOT patients with COVID-19 had higher comorbidities, greater levels of inflammatory markers at diagnosis, and higher rates of intensive care and hospital mortality. Pediatric CA patients and HCT patients with COVID-19 tended to have clinical presentations and outcomes similar to the general population. Interpretation: To our knowledge, this is the first systematic review evaluating COVID-19 phenotype and outcomes in immunocompromised patients and comparing them to the general population, which shows that hospital outcomes appear to be worse in adult CA and SOT patients, potentially due to their higher co-morbidity burden.

rapidly spread worldwide, causing a global pandemic with major social and economic disruption. Although the effects of COVID-19 have been greater in adults, children also are infected with SARS-CoV-2, and COVID-19 can lead to severe outcomes in pediatric patients (1-3). Nevertheless, the spectrum of clinical manifestations in children is broad and ranges from asymptomatic to mild upper respiratory infection to pneumonia or the more severe multisystem inflammatory syndrome in children (MIS-C), which typically occurs 2 to 6 weeks after acute SARS-CoV-2 infection (4-7).Since the COVID-19 pandemic began, different SARS-CoV-2 variants have circulated worldwide. In the United States, the first variant that replaced the original strain was the Alpha variant (B 1.1.7) that circulated during April-June 2021. The Delta variant (B1.617.2) followed soon after and became predominant during July-mid-December 2021. Since then, different sublineages of Omicron quickly replaced other variants as the predominant variant as of September 2022. These newer variants have demonstrated higher transmissibility and have disproportionally affected unvaccinated persons and other vulnerable populations including children; rates of hospitalization have increased 5-fold to 10-fold in children, depending on the variant and age group (8-13). Epidemiologic studies that rely on SARS-CoV-2 circulation patterns have provided robust information; however, the role of specific SARS-CoV-2 variants on clinical disease severity in children and adolescents with COVID-19 is not fully known.The objective of this study was to assess whether distinct SARS-CoV-2 variants were associated with differences in clinical and laboratory data and cycle threshold (Ct) values (as a surrogate of viral load) in children and adolescents with COVID-19. The Nationwide Children's Hospital (NCH; Columbus, OH, USA) Institutional Review Board approved the study (#STUDY00002002).

Background: Influenza is a major cause of morbidity and mortality worldwide. Following the 2009 pandemic, there was widened interest in studying influenza burden in all regions. However, since data from the World Health Organization (WHO) Middle East and North Africa (MENA) region remain limited, we aimed to contribute to the understanding of influenza burden in Lebanon. Methods: A retrospective chart review extending over a period of 8 seasons from Jan 1st, 2008 till June 30th, 2016 at a tertiary care center in Beirut was performed. All cases confirmed to have influenza based on rapid antigen detection or/and polymerase chain reaction on a respiratory sample were included for analysis. Data on epidemiology, clinical presentation, complications, antiviral use and mortality were collected for analysis.

BackgroundAlthough children with COVID-19 account for fewer hospitalizations than adults, many develop severe disease requiring intensive care treatment. Critical illness due to COVID-19 has been associated with lymphopenia and functional immune suppression. Myeloid-derived suppressor cells (MDSCs) potently suppress T cells and are significantly increased in adults with severe COVID-19. The role of MDSCs in the immune response of children with COVID-19 is unknown.AimsWe hypothesized that children with severe COVID-19 will have expansion of MDSC populations compared to those with milder disease, and that higher proportions of MDSCs will correlate with clinical outcomes.MethodsWe conducted a prospective, observational study on a convenience sample of children hospitalized with PCR-confirmed COVID-19 and pre-pandemic, uninfected healthy controls (HC). Blood samples were obtained within 48 h of admission and analyzed for MDSCs, T cells, and natural killer (NK) cells by flow cytometry. Demographic information and clinical outcomes were obtained from the electronic medical record and a dedicated survey built for this study.ResultsFifty children admitted to the hospital were enrolled; 28 diagnosed with symptomatic COVID-19 (10 requiring ICU admission) and 22 detected by universal screening (6 requiring ICU admission). We found that children with severe COVID-19 had a significantly higher percentage of MDSCs than those admitted to the ward and uninfected healthy controls. Increased percentages of MDSCs in peripheral blood mononuclear cells (PBMC) were associated with CD4+ T cell lymphopenia. MDSC expansion was associated with longer hospitalizations and need for respiratory support in children admitted with acute COVID-19.ConclusionThese findings suggest that MDSCs are part of the dysregulated immune responses observed in children with severe COVID-19 and may play a role in disease pathogenesis. Future mechanistic studies are required to further understand the function of MDSCs in the setting of SARS-CoV-2 infection in children.

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