Covid-19 crisis: China using potential vaccine since July, says official

China has been giving experimental coronavirus vaccines to groups facing high infection risks since July, a health official told state media. No vaccine has yet passed final, large-scale trials to prove it is safe and effective enough to protect people from contracting the virus that has led to almost 800,000 deaths worldwide. 

The aim is to boost the immunity of specific groups of people, including medical workers and those who work at food markets and in the transportation and service sectors, Zheng Zhongwei, a National Health Commission official, told state TV in an interview aired late on Saturday. 

The guidelines for emergency