England head coach Chris Silverwood has tested positive for COVID-19 while isolating in Melbourne, the country's cricket board (ECB) said on Sunday.

Silverwood was already due to miss the fourth Ashes test beginning in Sydney on Wednesday, having entered isolation last Thursday after a family member tested positive for the virus.

Assistant coach Graham Thorpe will lead England in Silverwood's absence. Australia have already retained the Ashes, leading the five-test series 3-0 with two matches to play.

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"England men's head coach Chris Silverwood has tested positive for COVID-19," the ECB said in a statement.

"He will remain in isolation until January 8. Silverwood is asymptomatic and is fully vaccinated.

"He is expected to return to the England party in Hobart ahead of the fifth Ashes test."

England's support staff have been depleted due to COVID-19 cases, with pace bowling coach Jon Lewis, spin mentor Jeetan Patel and fitness coach Darren Veness all in isolation in Melbourne.

Australia batsman Travis Head will miss also the Sydney test after testing positive for COVID-19.