[jandrese]

I think this works like condom statistics, where the statistic is that they are 98% effective, but that statistic includes people who go "we normally wear condoms, but we didn't that one time and she got pregnant" as a condom failure.

So basically, the masks are effective, but people take the masks off around family and friends and if one of their friends or family has COVID they will pass it on during the unmasked time.