@Nutmeg031992 @covidtweets I think numbers matter to an extent in terms of more vs. less transmissible virus. If a weak mask was good enough to make transmission unlikely in 5-10 minutes that's kind of effective for a grocery checkout. If it's more like 5-10 seconds, then it's pretty useless.
@肉豆蔻031992@covidtweets我认为数字在某种程度上取决于传播性更强的病毒和传播性较弱的病毒。如果一个虚弱的口罩足够好，在5-10分钟内不太可能传播，这对杂货店的结帐很有效。如果是5-10秒，那就没什么用了。