A recovered coronavirus patient from Huanan seafood market donates plasma at Wuhan Blood Center in Wuhan, capital of central China's Hubei Province, Feb. 17, 2020. Cured patients who were infected with 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. (Xinhua/Cai Yang)