Matt Greenshields never worried about COVID-19 until he found himself thinking about death as he was being wheeled down the empty, darkened hallways of a hospital on his way to intensive care.

His condition was complicated because he had already contracted mononucleosis. He's hoping his story will warn others to take the pandemic seriously.

Greenshields, 19, was attending the University of Calgary when he developed a runny nose and body aches on March 12.

He went home to Okotoks, about 60 kilometres south of Calgary, to recuperate, but his condition worsened: a cough, swollen lymph nodes in his neck and eventually extreme nausea.

Twelve days later, he was rushed to the South Health Campus.

"I got really, really nauseous and I coughed up a decent amount of brown mucus and blood with it. That's when we finally decided we've got to go to the hospital," Greenshields said in an interview with The Canadian Press on Wednesday.

He was tested for COVID-19, strep throat and two kinds of mono. But the real concern was that he might have lymphoma and doctors wanted to do a biopsy.

"I got admitted that night because they were going to do the biopsy the next morning. Then the COVID test ended up coming back positive, which is something that nobody expected at all, because it didn't explain the swelling in my throat and tonsils."

'It was just an eerie feeling'

The swelling in his throat got so severe that he couldn't swallow or talk and had to be fed using an IV. He was transferred to ICU and had oxygen tubes in his nose to help him breathe in case he had to have a tracheotomy.

"That's the first time I really felt that maybe I'm not going to be OK. The whole time I was kind of brushing it off. But then, when I was going through those hallways down to ICU, that's the first time I was actually really scared for myself," Greenshields said.

"I had to be taken through these separate hallways because of the COVID. The hallways were just completely empty and barren. ... It was just an eerie feeling: where am I going right now and what's going to happen?"

His condition started to improve slightly the next day and by March 31 he was discharged to self-isolate at his parents' home. He hopes his story will prove to be cautionary for others, especially young people like himself, who he said were still going to house parties and meeting up when restrictions were being brought in.

"I could see people on social media who were still having those gatherings. It's that invincibility factor at my age where they think they're not going to get it," he said.

"I originally didn't want to share my story because of how intense it was. I didn't want to scare people. But when I saw that people were still hanging out with their friends and ... not really caring, I (thought) maybe I should scare them into staying at home."

Greenshields received an all-clear from Alberta Health on Tuesday. He no longer has COVID-19 but still faces a couple of months at home to recover from his mono.