Piper Lowery, 12, was terrified of needles, so it didn't seem worth it to force her to get the flu shot, her mom, Pegy Lowery, told The Washington Post. When Piper came down with H1N1 with serious complications (a fever of 105, vomiting, and the beginnings of organ failure), it was much too late. Four days after her illness began, Piper died of these complications. Now, her mom wants everyone to know that the flu shot is not just a suggestion; it's a must. As a participant in the Fight the Flu Foundation's Flu Hat campaign, she's crocheted over 700 hats for kids in hospitals. (Knitting was a favorite pastime of Piper's, according to her obituary.) Inside each of the hat packages that go to these hospitals, there's information about the flu and the story of another mom whose child was killed. Most healthy adults who get the flu will recover without being hospitalized, according to the CDC, but it can and does cause serious complications for many people every year. Young children, older people, pregnant women, and people with preexisting health conditions are the most vulnerable. Between 1976 and 2007, flu-related deaths ranged from 3,000 to 49,000 per year, according to the latest estimates from the CDC. This year's flu vaccine will protect you from H1N1 (a.k.a. swine flu, which is what Piper had) as well as two other circulating flu viruses. The CDC suggests that everyone over six months get the injectable flu vaccine, unless they're allergic to any of the ingredients or have a history of Guillain-Barré Syndrome. Since circulating flu strains change, it's important to keep getting the shot every year. Because the flu spreads so easily, protecting yourself means also protecting others. So, even if you think you're invincible, you should do it for people like Piper who may be more prone to the very scary complications of the flu. Flu shots are available not only at doctors' offices but also at some pharmacies. Flu.gov has a search tool that'll help you find somewhere to get one near you. "I don't want it to happen to somebody else," Pegy told The Washington Post. "I don't want them to lose their child. It's pretty devastating. There's nothing like it."