The science on children not being significant vectors of COVID (and, by extension, school closures not being very effective) is actually reasonably well established:
That's not quite accurate, according to the article:
"“While school closure as a measure on its own is predicted to have a limited effectiveness in controlling Covid-19 transmission, when combined with intense social distancing it plays an important role in severing remaining contacts between households and thus ensuring transmission declines.”"
https://www.theguardian.com/education/2020/apr/06/school-clo...