Viral infections can suppress the innate immune system, leading to a low-level infection that triggers an adaptive immune response and potentially a cytokine explosion.

“Now, that being said, as the virus, using various techniques, proteins, things that it does, as it suppresses that immune system, you get this low-level of viral infection that goes on for days. And then finally, the adaptive immune system kicks in and you get this cytokine explosion that ends people up in the hospital with pneumonia.”