García-González, PaulinaTempio, FabianFuentes, CamilaMerino, ConsueloVargas, LeonardoSimon, ValeskaRamirez-Pereira, MirlianaRojas, VerónicaTobar, EduardoLandskron, GlaubenAraya, Juan PabloNavarrete, MarielaBastias, CarlaTordecilla, RocíoVaras, Macarena AMaturana, PabloMarcoleta, Andrés EAllende, Miguel LNaves, RodrigoHermoso, Marcela ASalazar-Onfray, FlavioLopez, MercedesBono, María-RosaOsorio, Fabiola2022-11-032022-11-032021-10-21Front Immunol. 2021 Oct 21;12:769059. doi: 10.3389/fimmu.2021.769059.1664-3224http://hdl.handle.net/20.500.12254/2588The prognosis of severe COVID-19 patients has motivated research communities to uncover mechanisms of SARS-CoV-2 pathogenesis also on a regional level. In this work, we aimed to understand the immunological dynamics of severe COVID-19 patients with different degrees of illness, and upon long-term recovery. We analyzed immune cellular subsets and SARS-CoV-2-specific antibody isotypes of 66 COVID-19 patients admitted to the Hospital Clínico Universidad de Chile, which were categorized according to the WHO ten-point clinical progression score. These included 29 moderate patients (score 4-5) and 37 severe patients under either high flow oxygen nasal cannula (18 patients, score 6), or invasive mechanical ventilation (19 patients, score 7-9), plus 28 convalescent patients and 28 healthy controls. Furthermore, six severe patients that recovered from the disease were longitudinally followed over 300 days. Our data indicate that severe COVID-19 patients display increased frequencies of plasmablasts, activated T cells and SARS-CoV-2-specific antibodies compared to moderate and convalescent patients. Remarkably, within the severe COVID-19 group, patients rapidly progressing into invasive mechanical ventilation show higher frequencies of plasmablasts, monocytes, eosinophils, Th1 cells and SARS-CoV-2-specific IgG than patients under high flow oxygen nasal cannula. These findings demonstrate that severe COVID-19 patients progressing into invasive mechanical ventilation show a distinctive type of immunity. In addition, patients that recover from severe COVID-19 begin to regain normal proportions of immune cells 100 days after hospital discharge and maintain high levels of SARS-CoV-2-specific IgG throughout the study, which is an indicative sign of immunological memory. Thus, this work can provide useful information to better understand the diverse outcomes of severe COVID-19 pathogenesis.en-USAtribución-NoComercial-CompartirIgual 3.0 Chile (CC BY-NC-SA 3.0 CL)Severe COVID-19Oxygen therapyInvasive mechanical ventilationImmunityImmunological memoryArtículohttps://doi.org/10.3389/fimmu.2021.769059