And all of those secondary health issues are a direct result of the infection with the influenza virus. I do not think most people realize just how much an influenza infection leaves one vulnerable to other issues.
The thing about the vaccine is that even if it does not protect against the exact influenza strain that is circulating, it still provides partial protection if the circulating strain is similar to the one in the vaccine. With partial protection, you can still get sick but not as sick.
In Seniors especially per-existing heart issues of various forms are common, so are lung issues COPD and Emphysema are common. Diabetics are another group at risk. We’ve had what looked like healthy ball players drop dead of heart issues they didn’t know they had nor showed up on routine exams they have to have.