Editor's note: This series tells the stories of selfless individuals, from medical workers to volunteers, who are bravely fighting the virus outbreak with extraordinary dedication.

Yu Wanjun, a 53-year-old doctor in Ningbo, Zhejiang province, has proved that perseverance can make a difference in the fight against the novel coronavirus.

Yu was rightly relentless in the case of one patient suspected of being infected by the virus. After initial tests failed to confirm infection, Yu persisted, conducting five tests over four days, until he finally made a definite diagnosis: The patient was indeed infected.

Yu, vice-president of Yinzhou People's Hospital in Ningbo, has been on the front line of Ningbo's battle with the virus for more than 10 days.

"When I am preoccupied with the patients and treatment methods, I don't have much time to be afraid of the virus," he said.

It was on Jan 20 that Yu was informed by phone that a pneumonia patient from the hospital's branch in Hengxi town was suspected of being infected with the novel coronavirus.

Based on his 30 years of medical experience, Yu, also an expert in respiratory medicine, had been on full alert and had begun to look up relevant documents as early as early December, when cases of pneumonia with an unknown cause began to be sporadically reported in Wuhan, the city that later turned out to be the epicenter of the virus outbreak.

"At that time, I prepared myself for the possible spread of the new virus and the return to duty during the Spring Festival holiday," Yu recalled.

In the middle of January, efforts to prevent and control the novel coronavirus were in full swing nationwide. Once told about the suspected case in Hengxi, Yu decided to receive the patient and immediately started a hospital contingency plan.

The patient, Li Tianpeng (a pseudonym) was sent to an isolation ward at Yinzhou People's Hospital and tested with the 2019-nCoV detection reagent. He was diagnosed with the coronavirus early on the morning of Jan 21, the first confirmed case in Ningbo.

At noon on Jan 24－Chinese Lunar New Year's Eve－another patient suspected of having the virus was sent to Yu's hospital. Initial RNA detection was unable to confirm the case, but Yu insisted on the patient being put under isolated medical observation.

Medical tests over the next three days also failed to confirm the case.

On the fourth day, Yu made a fifth attempt, improving the testing method of the sputum sampling, and this time the patient was finally confirmed to be infected by the novel coronavirus.

"This is a traditional hidden case, as the virus is very concealing and a patient can be infected with little clinical manifestation. This poses huge challenges to doctors," Yu said.

By the end of January, seven of the eight wards in the hospital's isolation area were occupied by infected patients.

Yu checks patients' conditions every morning and offers words of comfort. He said his efforts and words give confidence to patients as well as young medical workers.

Li, the early patient, told the Ningbo Evening News that every time he sees the doctor, he feels secure.

Yu, when asked whether he has felt the stress or is afraid of becoming infected himself, quoted what a doctor said during the outbreak of SARS in 2003, saying, "When a person is truly concerned with others, he will have no time to think about himself."

Qin Jirong contributed to this story.