Australia cricket coach Matthew Mott admits he's "flabbergasted" more Women's World Cup players haven't contracted COVID-19 during the tournament.

Ash Gardner is the only tournament player to be isolated due to the virus to date, in part due to the diligence being displayed by the teams and the lack of a testing regime.

New Zealand is experiencing its worst COVID-19 outbreak of the pandemic, with more than 20,000 people testing positive each day.

More than four per cent of the population is infected, but public health officials believe the true number of Kiwis with the virus is higher.

Given it's been more than two weeks since Australia exited quarantine in New Zealand, Mott said he couldn't believe more of his players haven't tested positive.

"I'm flabbergasted, to be honest," he said.

"There were a few nervous people around when Ash went down … we were mindful that if we have it that it didn't take down three or four players.

"That's when it's going to have a huge impact.

The ICC, however, has adopted a form of don't ask, don't tell in its COVID-19 approach.

Gardner tested positive in a round of routine rapid antigen tests prior to the tournament.

Now the tournament is on, players are only tested if they are symptomatic and want to be tested.

The absence of a testing regime means there is less chance of COVID-19 absences, but it also heightens the chance there are positive but asymptomatic players competing.

An ICC spokesman confirmed to AAP the tournament was operating under a "test if required" model.

"When we have symptoms, we've got all the stuff that we need to do the RAT and if it needs to be elevated from there, it will be," Mott said.

Gardner's positive test came as Australia was due to leave camp in Christchurch to begin the campaign.

Instead of boarding the plane to Hamilton with her teammates, she stayed behind in a hotel room to serve her mandatory isolation.

"She's in pretty good spirits. She's been able to get some fresh air and get outside every now and then and feel normal," Mott told AAP.

"She also feels like it was probably the right end of the tournament for it to happen, if it had to happen.

A change to NZ's COVID-19 regulations means Gardner can link up with the squad on Saturday in the lead-up to Sunday's match against New Zealand.

"We're certainly planning for her to try and play," Mott said.

"Ash was as diligent as anyone and I can't work out how it happened … it was just unlucky — and very lucky it didn't spread any further."

Mott confirmed Tahlia McGrath is available for selection after being rested for the win over Pakistan with a sore heel.

AAP/ABC