Beijing/Singapore: CanSino Biologics Inc, one of many companies worldwide trying to develop a coronavirus vaccine, needs to conduct late-stage trials overseas if it is to stay in the race, experts say, but it has yet to announce another country willing to help.Mid-stage trials showed that its vaccine did not work as well in people with immunity to a particular strain of the common cold virus and experts say it needs to broaden its pool of testing in Phase III trials to see if that outcome, described by the company as "the biggest obstacle", is replicated abroad.With other countries pushing ahead with their own tests and deepening tensions with the United States posing a challenge to international collaboration, time is not on its side.A.