This photo taken on February 4, 2020 shows a medical staff member showing a test tube after taking samples taken from a person to be tested for the new coronavirus at a quarantine zone in Wuhan, the epicentre of the outbreak, in China's central Hubei province. - The world has a "window of opportunity" to halt the spread of a deadly new virus, global health experts said, as the number of people infected in China jumped to 24,000 and millions more were ordered to stay indoors. (Photo by STR / AFP) / China OUT (Photo by STR/AFP via Getty Images)
