The cellular immune system, particularly T cells, is highly effective at fighting viral infections and cancer.

“These T cells, which are the ones that fight viruses, are unbelievable. When you think about how many antibiotics we have in our arsenal to fight bacterial infections, it's remarkable. Think about how many antiviral drugs we have relative to antibiotics. We have very few and we certainly don't have them for the most common viruses we acquire. And yet, virtually all of us recover in the end unharmed from the typical viral infection we get two to three times a year. That's a testament how amazing our immune system is. And when you unleash it against cancer, it's effective 99.9% of the time.”