Cricket Australia chief Nick Hockley on Monday became the latest person to contract Covid-19 during the Ashes series against England.

Hockley, who is fully vaccinated, developed mild symptoms and immediately got tested and isolated, with a positive PCR result confirmed.

"I am isolating at home with my family, who have returned negative results," he said.

Hockley has had no direct contact with either the Australian or England squads, in line with Cricket Australia's biosecurity protocols for the tour.

Australian batsman Travis Head tested positive last week and has been ruled out of the fourth Ashes Test starting in Sydney on Wednesday, with Usman Khawaja expected to replace him.

Opener Marcus Harris, who was a close contact of Head, was kept away from a charter flight moving the team to Sydney from Melbourne on Friday as a precaution.

It meant he and standby players Mitchell Marsh and Josh Inglis had to drive themselves the nearly 900 kilometres (600 miles) between the two cities to join the squad.

The England camp have also been hit hard over the past week, registering at least seven positive cases among support staff and family members.

They reportedly include coach Chris Silverwood, fast bowling coach Jon Lewis, spin coach Jeetan Patel and strength and conditioning boss Darren Veness.

Batting coach Graham Thorpe is expected to take over as head coach for the Sydney Test.