The animal studies which have been done ahead of time so far, including some challenge studies in monkeys, suggest that this class of vaccine may not prevent transmission ,” Nolan said. That could result in authorities significantly prolonging their pandemic restrictions. Plans for unrestricted international travel for those with a “ health passport ” showing they have been vaccinated, for example, might have to wait.

https://www.scmp.com/week-asia/health-environ...oronavirus