A China-developed COVID-19 vaccine has passed the 50 percent threshold for efficacy in late-stage trials in Brazil, The Wall Street Journal (WSJ) has reported. It means the vaccine is considered viable by international scientists and can be put into use. The vaccine, CoronaVac, was developed by a Chinese biopharmaceutical producer Sinovac Biotech. It has completed phase III trials in Brazil and is also being tested in some other countries. China is at the forefront of global COVID-19 vaccine development, with most jabs undergoing phase-3 clinical trials, a health official said at a news conference Monday. As of Dec. 2, a total of 15 vaccine candidates developed in China had entered clinical trials, of which five are in phase-3, said Zheng Zhongwei, an official with the National Health Commission and head of a national working group for vaccine development, citing statistics from the World Health Organization.