Warning China faces 'colossal outbreak' from US-style reopening

China would risk a "colossal outbreak" of more than 600,000 daily COVID-19 cases if it followed a US-style reopening, experts have warned.

The chilling scenario was raised in a Peking University study that examined what would happen if China dropped its zero-tolerance pandemic policy, the Bloomberg news agency reports.

Experts projected the results if Chinese authorities followed other countries by lifting strict travel bans.

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Studying figures for August from the US, Britain, Israel, Spain and France, the Chinese researchers looked at the potential results if China adopted similar pandemic policies to those nations.

They estimated that China would have more than 637,155 daily COVID-19 cases if it followed the American strategy. The US had an average of 150,098 daily cases towards the end of August.

"The estimates revealed the real possibility of a colossal outbreak which would almost certainly induce an unaffordable burden on the medical system," the report said.

The study found China would have had 454,198 transmissions if it took the same approach as France and 275,793 cases if it followed the UK policy.

China reported 23 new cases on Saturday, down from 25 a day earlier.

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The report said China is not ready for reopening on the basis of Western-style mass vaccination strategies.

China has some of the toughest quarantine and border restrictions for overseas travellers.

The emergence of the Omicron Covid variant - designated "as of concern" by the World Health Organisation - has prompted other nations, including Australia, to introduce similar restrictions.