An excerpt from an article on ZH. The study in Iceland is what got my attention.
A study in Switzerland, including a review of World Health Organization contact tracing, failed to find evidence of a single case of a child passing coronavirus to an adult. A comprehensive study in Iceland isolated SARS-CoV-2 samples from every positive case, sequenced the virus genome, and tracked the mutation patterns. This analysis, along with contact tracing, allowed researchers to identify definitively who passed the virus to whom. The study concluded “[E]ven if children do get infected, they are less likely to transmit the disease to others than adults. We have not found a single instance of a child infecting parents.” A study of schools in Ireland found “no evidence of secondary transmission of COVID-19 from children attending school.”