The flu virus has a path around the globe that it takes. The vaccines we get are developed from the origination in Asia. Between that origination and it's arrival here in North America, it may have mutated, etc. So the flu vaccine may not be that effective.
Many deaths from the "flu" have a final result of pneumonia. It's a standard progression. So, while technically one may have died of pneumonia, they wouldn't have gotten pneumonia if they hadn't gotten the flu.
Even more important than washing your hands is to blow your nose often and don't sniffle. Every time you sniffle, you suck the gook into your bronchial tubes. That will turn your flu into bronchitis. Then it's just a quick jaunt into the lungs and pneumonia.