Keep reading healthy adults and children dying from flu. How is this even happening? Why does it happen to some healthy people?

Old/young/pregnant. Flu is often a moderate illness at worst.Yet we loose hundreds of old/kids & pregnant every year.Many die from flu pneumonia or bacterial co-infections.Some are the vulnerable chronically ill, but some were perfectly healthy before getting the flu.Many skip the vaccine because they don't think its worth it. I have taken one yearly since the late 70's because I know what it can do.
Severity of disease. The epidemic flu that sweeps the country every year causes very severe symptoms usually makes healthy people sick for a week or more. Most healthy people do recover, but, if the infection is very strong, and people get bacterial complications that Infect various parts of the body, and they don't get to the proper medical services in time, they die from the complications. The flu shot may help prevent or at least reduce the severity of the disease.