@danaludwig @mliffmann @MIJudy @DrEricDing @whca @maxwelltani What you quoted said that people were contagious before testing positive, but if they're still contagious after testing positive then requiring a negative test would REDUCE risk (i.e. filter out some contagious people). Maybe by not a lot, though.
@danaludwig@mliffmann@MIJudy@drericing@whca@maxwelltani你引用的话说，检测呈阳性之前，人们是有传染性的，但如果检测呈阳性之后，他们仍然有传染性，那么要求进行阴性检测将降低风险（即过滤掉一些有传染性的人）。不过可能不会太多。