Remember Daniel F Gudbjartsson's Icelandic study early 2020 showing children had no (zero) infections: "Spread of SARS-CoV-2 in the Icelandic Population", so why did we lock them down?

Children under 10 years of age were less likely to receive a positive result than were persons 10 years of age or older, in the population screening, no child under 10 years of age had a positive test

We did not need the evidence from this study but the evidence was good and it added to the already existing body of evidence showing children were at low risk of infection in the first place.

SOURCE:

https://pubmed.ncbi.nlm.nih.gov/32289214/

In a population-based study in Iceland, children under 10 years of age and females had a lower incidence of SARS-CoV-2 infection than adolescents or adults and males.’