I talked to a cousin who is a cardiac nurse in a large hospital, and he explained that there are (something to the effect of) primary, secondary, tertiary, and contributing causes of death. For example, influenza is almost never the primary cause of death. Usually you'll get something like (and I'm going on memory from a two-month-old conversation) primary cause is bronchitis or pneumonia with influenza either a secondary cause or contributing factor. Would the bronchitis had killed the patient without the severity amped up by the flu? Most likely not, as we can treat/cure bronchitis rather easily. But while the flu wasn't the primary cause, it was the driver behind the death, as the patient wouldn't have likely been dead without the flu's interaction.