Adrenaline can suppress innate immune responses, which is beneficial in the short term for enduring stress.

“Why? Because adrenaline actually suppresses a lot of these innate immune responses in a way that's healthy in the short term. This is why you can work, work, work, work, work, where you can study for finals, or you can take care of a loved one and then you finally stop and rest and go on vacation, and then you get sick.”