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.

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.

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.