That’s the title of a medRxiv preprint (unpeer-reviewed) paper that looked at the risk to adults—in particular, Scottish NHS healthcare workers, NHS-contracted general practice service providers, and members of their households—of contracting the Wuhan Virus (my term) when they lived in households with children with ages ranging from new-born to 11 years old. Total participants numbered more than 300,000 adults and children.
The results are correlative rather than causative, but the strength of the correlation is strongly suggestive.
The risk of hospitalization with COVID-19 was lower in those with one child and lower still in those with two or more children….
And the money quote:
Conclusion[:] Increased household exposure to young children was associated with an attenuated risk of testing positive for SARS-CoV-2 and appeared to also be associated with an attenuated risk of COVID-19 disease severe enough to require hospitalisation.
That suggests, also (my conclusion; the authors didn’t address the matter), that putting children back in school (at least grade school) poses no serious risk of spreading serious illness from the virus.
The preprint abstract can be read here.