They then spent hours queuing outside hospital on Wednesday.
"They were tested outside and it came back positive. Then they later went home and were feeling miserable for a couple days and taking a lot of paracetamol," Baker said.
"Now they're feeling a bit better."
He said it wasn't known yet whether the virus was the Delta or Omicron variants – both of which have been responsible for disastrous waves in New South Wales.
Daily cases in NSW surged past 38,000 on Friday – a new daily record – while Covid-19 admissions in the state's hospitals doubled to more than 1700.
"From a public health point of view, I'm arguing for New Zealand to screw down the borders to limit transmission," Baker said.
"But from a personal point of view, it's actually quite painful, because it's going to make it harder for him to come back and study.
"I think everyone's affected, aren't they?"