Immune response to COVID-19 in older adults

Abstract

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the third highly pathogenic coronavirus to emerge in the human population in last two decades. SARS-CoV-2 spread from Wuhan, China, across the globe, causing an unprecedented public healthcare crisis. The virus showed remarkable age dependent pathology, with symptoms resembling common cold in most adults and children while causing more severe respiratory distress and significant mortality in older and frail humans. Even before the SARS-CoV-2 outbreak infectious diseases represented one of the major causes of death of older adults. Loss of immune function and reduced protection from infectious agents with age - immunosenescence - is a result of complex mechanisms affecting production and maintenance of immune cells as well as the initiation, maintenance and termination of properly directed immune responses. Here we briefly discuss the current knowledge on how this process affects age-dependent outcomes of SARS-CoV-2 infection.

Keywords: COVID-19; Sars-CoV-2; aging; immunity; severity.

Figure 1

Severe cases of COVID-19 are characterized by prolonged hyperactivation of innate immunity manifested by increased levels of inflammatory cytokines in circulation, also called “cytokine storm” as well as increased neutrophil count. This primarily occurs in aged and frail subjects. Development of successful vaccine shows that early adaptive immune response from T cells and neutralizing antibodies is protective and prevents the severe course of COVID-19.