@Marco_Piani Also, challenge trials were planned but not needed because of easy access to "naturally-infected" people. But if everyone had been as successful as say Western Australia, we would have done that and it would have worked fine.
@Marco_Piani还计划了挑战性试验，但由于很容易接触到“自然感染”的人，因此不需要。但是，如果每个人都像西澳大利亚州那样成功，我们就会做到这一点，而且效果会很好。