Until a routine Wednesday morning at his practice in north Sydney, Dr Warren Lee was in fine health.

An avid cyclist, he said he always liked to think of himself as reasonably fit.

But on that morning in April at around 11:30, half way through his flu clinic, the 50-year-old noticed his throat was sore.

“We were wearing masks and full-sleeved gowns. I thought: ‘This is not good’. But it didn’t feel like anything unusual, just a scratchy throat.”