One imagines that public health authorities place a very high value on maintaining their credibility. So, when they decide to gamble their credibility by publishing and enthusiastically backing a misleading and sloppy study, you have to wonder what made the health officials believe it was worth it.

Rochelle Walensky, who is President Joe Biden’s director of the Centers for Disease Control and Prevention, has spent months touting a study that purports to show a massive benefit from forcing little children to wear masks all day at school. That study shows nothing of the sort.