A cured coronavirus patient donates plasma at Hainan Blood Center in Haikou, south China's Hainan Province, Feb. 17, 2020. Cured patients who were infected with the novel coronavirus disease (COVID-19) are called upon to donate plasma as initial results had indicated the effectiveness of convalescent plasma-derived therapeutic products in curing infected patients in severe and critical conditions. Some recovered patients regard the donation as a way to pay back to the society after they received timely and effective treatment. (Photo by Zhang Liyun/Xinhua)