After fighting viruses for much of her 28-year career, Yang Yunkai, said she was mentally "immune" to the raging novel coronavirus and was determined to join in a team to develop a COVID-19 vaccine that will help put an end to the pandemic.

 Because the virus was well under control on the Chinese mainland by the time phase 3 was ready to begin, it was necessary to conduct it elsewhere

Yang, vice-director of the China National Biotec Group's clinical medical center, was responsible for the technical matters during the phase 3 trial of CNBG's COVID-19 vaccine development, which was filled with difficulties and challenges that tested her team.

"The data from third phase was vital to the final market approval," Yang, 49, said.

Unlike the previous two phases, the phase 3 trial needed to be carried out in places where the COVID-19 pandemic remains uncontrolled, offering trial subjects opportunities exposed to the virus. Because the virus was well under control on the Chinese mainland by the time phase 3 was ready to begin, it was necessary to conduct it elsewhere.

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After considering various countries and regions to hold the phase 3 trial for the inactivated COVID-19 vaccine, CNBG choose the United Arab Emirates. The company received official approval to hold the trial there on June 23.

CNBG was the first domestic medical company to carry out a trial for a COVID-19 vaccine overseas.

"We chose the UAE not only because of long-standing friendship and mutual trust between the two countries, but because of the great support from both governments," said Zhu Jingjin, the CNBG's Party secretary.

"The UAE is an ideal partner as they are endeavoring to transform into a technology-driven country from a resource-consuming one, which emphasizes more of its health industry."

Having been involved in COVID-19 vaccine development since last year's Spring Festival in late January, Yang was instructed to go to the UAE in early July as part of the "Great Wall" squad.

"I've participated in the campaign from the very beginning, and I am responsible for continuing the trial," she said.

Led by Zhu, Yang and her 28 team members, left for the UAE from Beijing on July 9. Yang said she felt sad when she saw the then-empty airport at departure.

"I had only one thought in my mind then, a strong sense of mission and a commitment to make the COVID-19 vaccine available to the public," she said. "It's not only for people's health, but to help them to get back normal life."

However, challenges awaited the squad when it arrived in Abu Dhabi, the UAE capital.

The first problem they faced there was the severe pandemic. Daily reported virus cases exceeded 1,000 at the time, posing a great risk to the team.

The sweltering weather was another issue. At that time, Yang's team members needed to travel back and forth between the airport and cold storage to preserve vaccines being flown in. The temperature difference was as high as 40 to 50 C, threatening their physical performance.

"We didn't even bring warm clothes with us, so we had to buy coats at local malls. Some of my colleagues asked our domestic peers to mail clothes," Yang said.

The cuisine was another obstacle. The squad members didn't care for the regional food, which consisted of olives and porridge-like dishes, so they mainly ate chili sauce and instant noodles they had brought with them.

Furthermore, their endured difficult work schedules.

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"We didn't have any days off during the trial," Yang said. "We worked more than 12 hours a day, and it was common to stay up all night. We had to get used to eating lunch at 4 pm and getting back to our encampment at 1 am. When we felt we were going to pass out, we would usually take short naps before getting up to continue the work."

The team members overcame their problems with patience and tenacity, and their hard work eventually paid off. After working for 186 days in the UAE, they got the data they needed from the phase 3 trial to prove the COVID-19 vaccine was safe and effective.

The inactivated vaccine developed by CNBG was granted conditional approval by the National Medical Products Administration in late December. The squad returned to China shortly afterward without anyone being infected by the virus.