Walker McKnight remembers that first time he took a hit off of a Juul e-cigarette. “It was a really intense, good feeling,” he tells PEOPLE. “I could feel my whole body throbbing and tingling.” Three months later, the 19-year-old college cheerleader was fighting a desperate battle to stay alive.

For over five months he drifted in and out of consciousness, connected to a respirator in an Orlando, Fla., hospital. Doctors fought to keep his inflamed lungs from collapsing and his organs from shutting down. “I begged my parents to let me die,” says Walker. “I wouldn’t wish this on anybody.”

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“His case is the worst I’ve seen so far,” recalls critical care specialist Dr. Charles Hunley with Orlando’s Regional Medical Center, which has treated six vaping-related cases in recent months. “Walker was literally dying in front of our eyes.”

Described by CDC officials as an “alarming epidemic” that has left 2,290 people with lung injuries and has been linked to 47 deaths, according to the agency’s figures. “No youth, young person or pregnant women should be using any e-cigarette or vaping product,” Dr. Anne Schuchat, principal deputy director of the CDC tells PEOPLE. “Lung injury associated with e-cigarette or vaping product use is serious and potentially fatal.”

Walker admits that he was oblivious to the potential dangers of vaping last December when he purchased his first Juul device, along with a package of tiny mango-flavored pods that contained a pack of cigarette’s worth of liquid nicotine, at a gas station near his parent’s home in Orlando.

“After about a week and a half I stopped getting buzzed from it,” he recalls, “but I’d get nervous and twitchy if I didn’t have it.” For the next three months, Walker tried convincing himself that “if I want to give it up, I’ll just give it up. But by then I was hooked on it just like everyone else.”

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By early March, Walker couldn’t hold any food down and had fevers and chills. Doctors at the emergency room near the Florida Atlantic University campus told him he had the flu and prescribed antibiotics and steroids. Four days later, his condition worsened.

“My chest hurt so bad I couldn’t even see straight,” says Walker, who managed to drive himself 200 miles back to his parents’ home in Orlando. “I’d never seen anyone so sick in all my life,” says his father Dave, who rushed his son to a nearby urgent care clinic. Doctors insisted that he needed to go to a hospital emergency room where x-rays quickly revealed that he had what appeared to be pneumonia in his left lung—and he was immediately admitted to ICU. “No one asked me if I vaped,” recalls Walker. “They just asked me if I smoked and I told them I didn’t.”

Within days, he was connected to a respirator, then airlifted to another hospital, put in a medically-induced coma and hooked up to ECMO machine that pumped and oxygenated his blood outside of his body, allowing his lungs and heart to rest. “We lost him five times,” recalls his mom, Candy, who works as a critical care nurse. Doctors eventually determined that his infection was caused by adenovirus—often found in college dorms that normally only leads to a mild illness—but they were stumped over how this could happen to an otherwise healthy college athlete.

The answer came into focus after Walker’s parents went to clean out his dorm room and were horrified by what they found. “I opened up his desk drawer and it was filled with Juul pods,” recalls Dave. When Candy relayed the information about her son’s vaping habits to his physicians, it solved the mystery of why Walker’s lungs had become so weak that a relatively benign virus could nearly kill him.

When Walker left the hospital in July, he had lost 80 lbs., and his left lung and both his kidneys were destroyed. He carries an oxygen tank with him wherever he goes, and will have to endure grueling lung and kidney transplants to survive (The McKnights are raising money for his medical bills on GoFundMe). Now at 20 years old, Walker’s life revolves around dialysis sessions, physical therapy, doctors’ appointments and twice-a-day naps. “This is like something I used to think only happened in the movies,” he says.