Editor's note: Nations are collaborating in the fight against the novel coronavirus pneumonia outbreak to limit the damage to people's health and the impact on the global economy. Here, in the third part of a series titled "One World, One Fight", we look at how countries can work together.

On the evening of Feb 28, when Chen Yangxue returned to her home in downtown Seoul from her job at a trading company, she saw a notice on the door stating: "We kindly ask you to visit a nearby health institution to test for the novel coronavirus."

Chen, who is from Weihai, Shandong province, and has lived in the South Korean capital for more than 10 years, said, "When I saw the notice, I felt very nervous because I had heard on the news that the outbreak in South Korea was the worst outside of China."

She said she rang the consultation number on the notice. After giving her address, a staff member at the Korea Centers for Disease Control and Prevention, or KCDC, said that a resident living in Chen's neighborhood was a "suspected case" and all residents in the community must be tested.

"The staff member said the entire test would take less than 10 minutes, the results would be sent to my phone, and the process would be free," Chen said.

Two days later, she received a message on her phone stating that she had tested negative. "I felt hugely relieved," she said.

Chen said she was very lucky, as on the day she took the test-Feb 29-South Korea reported 909 new cases of novel coronavirus pneumonia, the highest number confirmed in a single day, according to the KCDC.