Actress Michelle Ye reads Xu's wife's letter as part of the show. [Photo provided to China Daily]

Explaining how he decided to lead his team－including another four young doctors－to take an additional 14-day shift, Cai writes: "Even if there could be enough substitutes to take over our job, I don't want to retreat and rest. I just want to work at the hospital to save as many patients as possible … I may get infected one day … but I have no fear."

China has implemented an isolation policy to urge people to avoid unnecessary trips, thus letter writing is one of the most important means to express feelings, says Guan.

"But it was a big problem for us to figure out how to produce the new season. It's obviously impractical to build stages and organize an audience as well as to use professional facilities to shoot the scenes," adds Guan.

With footage shot by stars through their own smartphones, the crew has worked on a tight schedule to edit the videos by adding music and news photos.

"It only took four days from when we decided to make such a season to when the first episode was released online. Most of our young colleagues slept only a few hours and the stars also overcame difficulties such as learning by themselves how to manipulate light during filming," says Guan.

"For us, the new content might be a bit coarse, but it will be part of the collective memory to commemorate this special time," he concludes.