Parents Share Heartbreaking Warning About Their Girl's Deadly Decision

After Gwen and Terry Zwanziger's otherwise healthy teenage daughter died from a simple case of the flu, they are speaking out to warn other parents.

It's been more than 836 days since Shannon's death, but for her mom, the situation is still just as scary as ever. When Shannon came to her with a sore throat and a low fever, Gwen wasn't alarmed and now two years later, she can only hope her daughter knows how sorry she is for not fighting her.

At 17 years old, Shannon didn't want to get the flu vaccine and now her mom is left dealing with the guilt of not insisting on it. "If I had pushed her into getting a flu shot, then I wouldn't have the guilt about 'what if,'" Gwen told CNN. "What if the vaccine had given her a little extra control over the invasion? That's what the vaccine should do. While you can still get the flu even if you've had a flu shot, it can reduce the risk of serious illness and complications."

But instead, Shannon came home from school complaining that a classmate gave her the flu. So Gwen sent her to her room with an array of fluids and medicine. When Shannon didn't seem to be improving a few days later, her dad took her to a clinic while her mom stayed back to clean her room and change her sheets. "Terry sent me a picture of Shannon sitting in a wheelchair with a mask on, leaning her head on his shoulder," Gwen said. "That's the last picture we have of her."

The doctor advised that they just "let it run its course," but 36 hours later Shannon came downstairs and asked for help taking a bath. By this point her mom was "sweating in fear" because she hadn't helped her daughter bathe since she was a small child. "Something was horribly wrong. When she leaned back in the tub and I saw her eyes, I knew she was dying," she said. "I got behind her and lifted her out. I sat on the toilet with her sitting on my lap and she died. There was nothing that could be done to save her."

Gwen explained that the flu destroyed her daughter's organs without her even knowing it and there was nothing that could be done to revive her.