Katerina Tsantou, 34, who received a heart transplant at Onassis Cardiac Surgery Center seven years ago, attends the Hellenic Transplant Organization's social awareness event in Athens, Greece, on April 15, 2019. Greece aims to double the rate of human organ donations for transplants within the next two years, the President of the Hellenic Transplant Organization (EOM), Andreas Karabinis, told Xinhua on Monday. (Xinhua/Marios Lolos)