The director of the National Centre for Infectious Diseases has said the nation is expected to reach the peak of Covid infections within a week.

Zhang Wenhong's comments – quoted in Shanghai government-backed news outlet The Paper on Thursday – came as mainland officials reported less than 4,000 new symptomatic local Covid cases nationwide for December 22, and no new Covid deaths for a third straight day.

"The peak infection will also increase the rate of severe disease, which will have a certain impact on our entire medical resources,” he said, adding the wave will last another one or two months after that.

"We must be mentally prepared that infection is inevitable."

Nevertheless, Zhang said he had visited nursing homes around Shanghai, noticing the number of elderly dealing with severe symptoms was low.

But a Shanghai hospital had estimated half of the commercial hub's 25 million people would get infected by the end of next week.

US Secretary of State Antony Blinken, meanwhile, called on China to share information on its Covid outbreak, and said its caseload, which he described to be surging, had impacted the world.

"It is very important for all countries, including China, to focus on people getting vaccinated, making testing and treatment available and, importantly, sharing information with the world about what they're experiencing," Blinken told a news conference.

Separately, a Xinhua opinion piece said the mainland's constant optimisation of Covid strategies will save lives and the economy.

The news agency said mainland officials have rolled out a string of modified measures based on the evolving pandemic situation.

It added Beijing is better aligning anti-Covid efforts with economic and social development as the country shifts the focus of its coronavirus response strategy from infection control to case treatment to prevent severe cases. (Reuters/Xinhua)