The city collected 51,800 units of platelets last year, rising 5.1 percent from the previous year but still far from enough, according to Shanghai Blood Centre, which honored 634 regular platelet donors at the weekend.

At least 80,000 units are needed each year and, as platelets can only be stored for five days, regular donations are necessary. Platelets are important in treatment of leukemia, cancer and in stem cell transplants.

“We are encouraging more people, especially young people, to make regular donations,” said Lu Taohong, director of the center. “Since 2013, we have teamed up with the education authority to promote donations at universities.”

Last year, however, university students donated only 478 units of platelets and 27 units of blood.