Coronavirus disease 2019 (COVID-19) is a mild to moderate respiratory tract infection, however, a subset of patients progress to severe disease and respiratory failure. The mechanism of protective immunity in mild forms and the pathogenesis of severe COVID-19 associated with increased neutrophil counts and dysregulated immune responses remain unclear. In a dual-center, two-cohort study, we combined single-cell RNA-sequencing and single-cell proteomics of whole-blood and peripheral-blood mononuclear cells to determine changes in immune cell composition and activation in mild versus severe COVID-19 (242 samples from 109 individuals) over time. HLA-DR hi CD11c hi inflammatory monocytes with an interferon-stimulated gene signature were elevated in mild COVID-19. Severe COVID-19 was marked by occurrence of neutrophil precursors, as evidence of emergency myelopoiesis, dysfunctional mature neutrophils, and HLA-DR lo monocytes. Our study provides detailed insights into the systemic immune response to SARS-CoV-2 infection and reveals profound alterations in the myeloid cell compartment associated with severe COVID-19.

Highlights d SARS-CoV2 infection elicits dynamic changes of circulating cells in the blood d Severe COVID-19 is characterized by increased metabolically active plasmablasts d Elevation of IFN-activated megakaryocytes and erythroid cells in severe COVID-19 d Cell-type-specific expression signatures are associated with a fatal COVID-19 outcome

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Objectives Parkinson's disease (PD) is a progressive neurodegenerative disease that often impedes activities of daily living (ADL) and social functioning. Impairment in these areas can alter social roles by interfering with employment status, household management, friendships, and other relationships. Understanding how PD affects social functioning can help clinicians choose management strategies that mitigate these changes. Methods We conducted a mixed‐methods systematic review of existing literature on social roles and social functioning in PD. A tailored search strategy in five databases identified 51 full‐text reports that fulfilled the inclusion criteria and passed the quality appraisal. We aggregated and analyzed the results from these studies and then created a narrative summary. Results Our review demonstrates how PD causes many people to withdraw from their accustomed social roles and experience deficits in corresponding activities. We describe how PD symptoms (eg, tremor, facial masking, and neuropsychiatric symptoms) interfere with relationships (eg, couple, friends, and family) and precipitate earlier departure from the workforce. Additionally, several studies demonstrated that conventional PD therapy has little positive effect on social role functioning. Conclusions Our report presents critical insight into how PD affects social functioning and gives direction to future studies and interventions (eg, couple counseling and recreational activities).