FILE PHOTO: A logo is pictured on the headquarters of the World Health Organization (WHO) ahead of a meeting of the Emergency Committee on the novel coronavirus (2019-nCoV) in Geneva, Switzerland, January 30, 2020. REUTERS/Denis Balibouse

GENEVA/ZURICH: A sharp upward revision in China's coronavirus death toll on Friday (Apr 17) was "an attempt to leave no case undocumented" after medical services in Wuhan were overwhelmed at the start of the outbreak, the World Health Organization (WHO) said.