A woman had a severe case of the flu that led to cardiac arrest and a leg amputation after forgetting her flu shot. Now she's on a mission to get others vaccinated.

• Shari Hall told Insider that she was too "busy" to get her flu shot.
• The virus attacked her heart. Her circulation failed, and she lost a leg and part of a foot.

It was more than five months into flu season and Shari Hall of Brownsburg, Indiana, hadn't gotten around to having her annual flu shot.

"I had it every fall in my doctor's office," Hall told Insider. "It had been a busy year and it slipped my mind."

The 57-year-old grandmother then caught the flu. Her case was so severe, it went on to attack her heart. She spent weeks in a coma in the hospital. Surgeons ended up amputating her left leg and part of her right foot to keep her alive.

"I try to stay positive," Hall said of her situation. "But I miss everything I was able to do before I got sick." She is sharing her story now to spread awareness of why it is important to get the shot every year.

Hospitalization for the flu is relatively uncommon in the US, but the risk increases with age. Getting the flu vaccine lowers a person's risk of being hospitalized or experiencing complications like heart attack and stroke, according to Northwestern Medicine.

Hall said that she had been in good health before developing the flu. She needed a lot of energy, she said, to keep up with the kids who attended the daycare she ran from her home.

Hall has hazy memories of being sick in the hospital

One morning in February 2018, she woke up feeling weak and breathless. "My face was drooping and my eyes were bloodshot," she said. "I could barely stand up."

Hall's symptoms were the start of three weeks trying to survive followed by 10 more weeks in the hospital and a six-month stay at a rehabilitation center.

Hall said that she has only vague recollections of the traumatic period that her life was in the balance.

She said that she remembered her husband, Bill, driving her to the emergency room. She said that she had hazy memories of getting a nose swab and being told that she had the flu.

But her blood pressure was soaring. Bill said that a doctor listened to her heart and told him that something was wrong. An ambulance transported her to a larger hospital — where medical staff stabilized her — and then transferred her to a hospital in Indianapolis.

"She was unconscious," Bill told Insider.

Medical staff managed to restart Hall's heart using CPR

Bill said that members of the family had started to arrive at the hospital when he heard the alert, "Code Blue," over the loudspeaker. His wife had gone into cardiac arrest. He said that he ran along the hallway, but medical staff told him to stay out of Hall's room.

The doctors and nurses successfully performed CPR. But, Bill said, the doctor told him that her heart desperately needed support to keep her alive. He said that doctors then placed Hall in a medical coma. She later underwent surgery to place her on an ECMO machine, which pumps out blood and sends it through a heart-lung machine that removes all the carbon dioxide and sends oxygen full blood back into the body.

"It was heartbreaking to see those tubes, machines, and monitors," Bill said of the procedure during which the patient's blood is oxygenated outside of their body.

"You couldn't get within three feet of her bed because there was so much equipment," he said. "Two nurses stayed with Shari 24-7 and never left the room."

Hall went on to have four hours of heart surgery, in which doctors removed her ECMO. The operation was a success, but the doctors told Bill that "other issues" might cause complications.

A nurse practitioner told Hall that her left leg and part of her right foot were gone

She developed an infection a few days later, followed by sepsis. "The doctor said, 'Her legs aren't looking good,'" Bill said, noting that they'd turned black in color.

He said that Hall's medical team arrived and said, "We've got to amputate," adding that, "They explained that, if they didn't do it right now, the sepsis would kill her."

He gave the surgeons permission to remove Hall's left leg above the knee, a section of her right foot including her toes, and an index finger. Medical staff told him that there was a chance they'd have to remove other parts of her body, too. "I thought, 'I hope she's not going to be mad at me for the decision I made,'" Bill said. "'Is this something she won't want to come home to?'"

He said that Hall was in a coma for three weeks. "The kids and I were dreading being in her room when she woke up and realized what was going on with her leg," he said.

Bill said that a nurse practitioner told Hall about the amputations when they thought she was lucid enough to understand. "The nurse said, 'You were really really sick and we saved your life,'" Bill, who was at her bedside at the time, said.

He said that the nurse went on, "But this was part of what has happened."

Hall told Insider that she'd felt that something was wrong with her leg. "I can only describe it as a dangling feeling, as if it was dangling off the bed," she said.

She said that she knew that Bill had made the right decision about the amputations when she learned that she would have died without the surgery.

"I wanted to live for Bill, my kids, and my grandchildren," Hall said.

Hall wants others to take note of her experience and get their flu shots before it's too late

She now wears a prosthetic leg and an orthopedic shoe to support her right foot. She said that she had to spend a total of nine months away from home as a result of her illness.

Hall said she is telling her story as part of a public-awareness campaign called Not Today, Flu.She wants people to know about the dangers of the flu. While getting the flu shot may not have prevented her from being infected, the shot does lower the risk of heart-related complications from catching the virus.

"I look back and think, 'Yes, I was busy, but I should have taken 15 minutes out of my life to get the flu shot,'" she said.

"I'll never make that mistake again," Hall added.