"I was with my missus in the shower – because we always shower together. It's good.
"I was sitting in the shower. I started having a cough and pulled my back. That's how it happened.
"Am I worried about it? No. You need to make sure you have the right people around you to make sure you're right for the next round.
"The doctors don't know what has caused it. It could happen to anyone they say.
"The most important thing was my lung and heart were okay."
There will be a restricted world championships crowd of 1000 spectators at Alexandra Palace on Tuesday although they will then be excluded when London goes into a Tier 3 until December 23.
The 31-year-old van Gerwen lost the last world final to world number two Peter Wright, the Scot who has had trouble nailing titles throughout his career.
Van Gerwen will be the favourite again but has struggled during lockdown without the adrenaline rush the normally boisterous and packed arenas provide
"It's different for everyone but you have players who don't mind playing in front of no crowds," he said.
"I do mind. I'm a stage player. If crowds are against me or back me – I don't care. I want to perform for them, give it a go.
"The adrenaline in my body pumps up. I don't have that now."