The measures taken by China have effectively prevented the spread of the epidemic caused by the novel coronavirus (COVID-19), officials from the World Health Organization (WHO) said at a news briefing in Geneva on Tuesday.

China's health system has made great efforts to treat patients and reduce mortality rate and the WHO backs China's strict measures to stop the spread of the virus, they said. 

"Those measures on movement restriction have delayed the dissemination of the outbreak by two or three days within China, and two or three weeks outside China," said Sylvie Briand, head of the WHO's Global Infectious Hazard Preparedness division.

"The first objective in Wuhan was to contain the virus at the epicenter, and you've heard the director-general speak: Fight the virus at the epicenter. Suppressing that virus now allows space to really do much more active surveillance," said Michael Ryan, the executive director of WHO's Health Emergencies Program. 

"What China is trying to do is while they're getting success in putting out one fire, they don't want the fire to start somewhere else. So they're taking very directed measures to ensure the people returning to the city are observed and monitored," he added.

The WHO also said that vaccine candidates would be possible in 16 weeks, but relative tests would still take more time.

The organization called on countries to accelerate research on the novel coronavirus and share more case information with them.