system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When you read that flu has killed otherwise healthy people, what are the symptoms that actually take them out? Are they drowning in lung fluid or exhaustion from coughing, or what?
gpt
A few ways.  The flu can cause intense inflammation in your lungs and you can die from respiratory failure.   That's the most direct way (along with heart or organ failure, also brought on by inflammation).  

But the flu can kill you by making you susceptible to other bad stuff, too, because your body is weak and slow from trying to fight off the flu.  In fact the most common way to die from the flu is to get it and then get pneumonia as a result.  that's how the elderly usually go when it happens to them.