Testing, isolation, contact tracing – that's the message the World Health Organization has for every country to tackle the coronavirus pandemic.
Some have listened. Others haven't. Some have been able to turn the tide on the outbreak, others are still playing catch-up. Just like a professor handing out instructions before an exam, whoever listened, scored higher in the end. 

On-camera reporter: Serena Dong

Scriptwriter: Serena Dong

Video editor: Qi Jianqiang

Filmed by Qi Jianqiang

Chief editor: Wang Xin

Producer: Wen Yaru

Director: Zhang Shilei

Supervisor: Fan Yun