FIGURE 1.

Schematic shows age-related changes in the innate and adaptive immune system with relevance to COVID-19. As the SARS-CoV-2 enters parenchymal cells expressing the ACE2 receptor, it activates PRR of the innate immune system. With aging, there is an imbalance in cellular functions and signaling, decreasing innate activation of an already weakened adaptive immune system. These imbalances lead to “inflammaging” from proinflammatory innate immune responses and immunosenescence of the adaptive immune response.