The Formula 1 season is set to be suspended until May because of concerns over the coronavirus pandemic, meaning the Bahrain and Vietnam Grands Prix will not go ahead as scheduled.
The Bahrain Grand Prix was due to be held behind closed doors on 22 March but is set to be called off completely.
The Vietnam Grand Prix on 5 April is also not expected to go ahead.
The Australian and Chinese Grands Prix were already cancelled, with the Dutch Grand Prix scheduled for 3 May.
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Seven were cleared on Thursday but an eighth, from McLaren, tested positive.
The Vietnam Grand Prix is now expected to follow after the government in Hanoi banned travel into the country for anyone who has been in Italy – among other locations – in the previous 14 days.
The Chinese Grand Prix, scheduled to be the fourth race, was postponed in February after government officials said it could not go ahead.