(https://www.nytimes.com/2020/07/18/health/coronavirus-childr...)
However, Sweden did not close school for children through 14 years of age.
https://www.sciencemag.org/news/2020/05/how-sweden-wasted-ra...
And their excess mortality rates for that age group are indistinguishable from other European countries:
https://euromomo.eu/graphs-and-maps
When you go to that link, near the bottom select graphs by age and see that Sweden ages 0-14 looks like all the other countries shown there. I think that is a pretty good indication. We have a country that kept their schools open and a number of countries that did not, and the results look the same.
EDIT: in fact, the excess mortality for that age group looks indistinguishable from other years.