Arcanjo A, Pinto KG, Logullo J, et al. - Severe acutely infected patients with COVID-19 exhibit high levels of both type-1 and type-2 cytokines.

• T cell stimulation results in abnormal cytokine levels, in a non-polarized profile.

• In addition, there appears correlation of this hyperactive cytokine response with a significantly elevated frequency of late-differentiated T cells with particular phenotype of effector exhausted/senescent CD28 -CD57 + cells.

• Further, an increased frequency of CD3 +CD4 +CD28 -CD57 + T cells was demonstrated for the first time with expression of programmed death 1 (PD-1), one of the hallmarks of T cell exhaustion.

• According to these findings, COVID-19 is linked with acute immunodeficiency, especially within the CD4 + T cell compartment and there are possible mechanisms of loss of clonal repertoire and susceptibility to viral relapse and reinfection events.