Volunteers donate blood at a blood donation center in Cixi City, east China's Zhejiang Province, June 13, 2018, one day ahead of the World Blood Donor Day. A total of 4,600 people have donated 1.5 million milliliters of blood in Cixi City so far this year. (Xinhua/Xu Yu)

A volunteer receives medical checkup before donating blood at a blood donation center in Cixi City, east China's Zhejiang Province, June 13, 2018, one day ahead of the World Blood Donor Day. A total of 4,600 people have donated 1.5 million milliliters of blood in Cixi City so far this year. (Xinhua/Xu Yu)

Volunteers display certificates after donating blood at a blood donation center in Cixi City, east China's Zhejiang Province, June 13, 2018, one day ahead of the World Blood Donor Day. A total of 4,600 people have donated 1.5 million milliliters of blood in Cixi City so far this year. (Xinhua/Xu Yu)