TOPSHOT - In this picture taken on April 29, 2020, an engineer looks at monkey kidney cells as he make a test on an experimental vaccine for the COVID-19 coronavirus inside the Cells Culture Room laboratory at the Sinovac Biotech facilities in Beijing. - Sinovac Biotech, which is conducting one of the four clinical trials that have been authorised in China, has claimed great progress in its research and promising results among monkeys. LEHTIKUVA / AFP Nicolas Asfouri