Bird flu: Chinese Premier urges vigilance

Chinese Premier Li Keqiang is urging vigilance against a new strain of bird flu that has so far killed 23 people.

Mr Li says efforts to tackle the virus have so far been effective.

A leading American virologist says there's no evidence the deadly H7-N9 bird flu has yet spread between humans, but he has warned that health authorities must be ready for the virus to mutate at any time.

Russell Trott reports.