Challenges abound along the stretch of border that he and three peers guard day and night: the temperature plummets at night; mosquitoes and flies irritate the patrolmen as they sleep; and snakes hiss in the dark.

Li said he is undaunted and never bored. "I am unable to express just how proud I am and how much responsibility I feel on my shoulders," he said.

For Zhao Suying, joining the fight against the virus meant abandoning her specialty in rehabilitative medicine and playing a number of supporting roles at the hospital, such as managing the storage of medicines and antivirus materials, and delivering meals and medication to wards.

"Frankly, I questioned the significance of my role and felt menial from time to time," the 26-year-old said. "But I have come to realize that amid an outbreak, no position is insignificant."

In 2016, she graduated from the Yunnan University of Chinese Medicine in Kunming, the provincial capital. Since then, she has worked at the Chinese Medicine and Dai Ethnic Medicine Hospital, a designated center for COVID-19 patients in Ruili.

Since last year, different groups of medical aid teams from other parts of China have been stationed at the hospital. Whenever there are personnel changes, Zhao helps to familiarize the newcomers with the hospital setting.

"These experiences have shaped my personality and made me a tougher soldier against the common enemy－the virus," she said.

Sometimes, she becomes wistful, especially when she recalls how lively and exuberant Ruili was before the epidemic. "The city and its people have made many sacrifices to combat the virus," she said.

Ma Jiansong, the hospital's president, said nearly half the medical workers there are young people like Zhao. "They are energetic and hardworking. During the epidemic, they have learned a lot from medical aid experts and have grown up quickly," he said.