The World Health Organization has called for "immediate and concerted action" to protect children from contaminated medicines after a spate of child deaths linked to cough syrups last year.

China's population fell last year for the first time in six decades, a historic turn that is expected to mark the start of a long period of decline in its citizen numbers with profound implications for its economy and the world.

The drug aims to slow the advance of the neurodegenerative disease. Nearly all previous experimental drugs using the same approach have failed.

Cases were exploding in China well before the government's decision to abandon its strict "zero-COVID" policy, the director said, quashing suggestions that the sudden reversal caused a spike.

A week after China began dismantling its tough 'zero-COVID' controls, the World Health Organization warned of "very tough" times ahead and state media reported some seriously ill patients at hospitals in Beijing, raising fears of a wave of infections.

China should change its official name for COVID-19 to reflect the virus' mutation, and patients with light symptoms should be allowed to quarantine at home, a leading authority on traditional Chinese medicine was quoted as saying on Wednesday.

China's financial hub Shanghai said on Sunday it would reopen all schools including kindergartens, primary and middle schools on Sept. 1 after months of COVID-19 closures.