Chen Xuyan, director of Emergency and Critical Care at Tsinghua Changgung Hospital, while calling U.S.' progress in developing coronavirus vaccine "unusual," said that a vaccine needs to be tested on animals first to ensure that it's effective and safe before being tried on humans. "There is a set international timeline on this matter and these crucial steps cannot be skipped," she said.
Copyright © 2020 CGTN. Beijing ICP prepared NO.16065310-3