Beijing, Dec 22 : 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 press conference Monday. As of December 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, citing statistics from the World Health Organization, the Xinhua news agency reported. As phase-3 clinical trials of Chinese vaccines are underway in regions and countries not with the highest numbers of infections, it may take more time to obtain enough samples for the trials, said Zheng. Some of the Chinese vaccine developers have just obtained enough samples for interim analysis of phase-3 clinical trials, and are submitting related materials to the National Medical Products Administration, said Zheng, adding that only vaccines meeting certain standards will be allowed to enter the market. /IANS