Medical workers and administrative personnel donate blood at a blood donation bus in Dongyang, Zhejiang province, on Tuesday. [Photo by Bao Kangxuan/For China Daily]

When Jia Zengguang, a business owner in Weihai, Shandong province learned that blood and platelet donations were critically needed, he took a high-speed train to Jinan on Dec 31 and donated two doses of platelets.

"There was no need to hesitate," said the 32-year-old Jia, who has been donating blood and platelets regularly during the past decade.

"Jinan, as the province's capital, has a bigger demand for blood than other cities," he said.

Jia is not alone. Growing numbers of people are rolling up their sleeves at blood donation centers.

The reasons for a previous decline in the number of blood donors included COVID-19, seasonal illnesses like cold and influenza, and chilly weather, according to notices calling for donations.

January is the hardest month for Hohhot in the Inner Mongolia autonomous region, said Zhang Shuo, director of the region's blood bank.

"In January, Hohhot needs 150 units of blood every day, which requires 100 to 120 people to donate," said Zhang.

On the Chinese mainland, each unit represents 200 millimeters of blood. People can donate one or two units.

On Dec 28, a request for blood donations for a 9-month-old boy who was receiving medical treatment for leukemia in Hohhot went viral.

The boy's father, Li Yue, 28, was desperate for help and so published a video online. His cry was heard, and people rushed to donate for the boy within two days.

Many warmhearted residents came to help, the father said, adding that a stranger donated twice for his boy and even donated the 100 yuan ($15) he received from the blood center for nutrition.

Li was grateful but expressed his concern that his boy needs regular donations and that he continues to call on people for the next transfusions.

Wu Xiandeng, a doctor at Jinan Second People's Hospital, donated 400 milliliters on Jan 2.

"My wife told me my blood type A is critically needed, and she encouraged me to donate," said Wu.

"We are doing everything we can to increase blood donations to ensure patients can receive timely medical treatments. And more people are needed," said Geng Xiufeng, who works at the information office of the Jinan blood supply center.