If it helps, I have found a bit more data and expert opinion in the WSJ,
who have a table on relative class sizes from the OECD:
WSJ: Schools in Europe
https://www.wsj.com/articles/to-keep-schools-open-as-covid-surges-europe-isolates-infected-students-11599757836
[Germany:]
Authorities worked to reassure staff about the safety of returning.
If teachers refused to return to work,
a health assessment was offered to reassure them about their risk level if they contracted the disease.
The percentage of teacher absenteeism went from double digits to between 2% and 5% as a result,
according to Andreas Schleicher, director of education for the Organization for Economic Cooperation and Development.
Any infected students or teachers are quarantined, along with their contacts.
Only a handful of German schools closed down completely at the end of last school year
and have closed so far this fall.
“I don’t think anybody would do [school closures] again,”
said Mr. Schleicher,
referring to European schools in general.
“It’s so much easier to close schools than reopen them.”
The emphasis on closing schools only as a last resort has come amid mounting evidence that children play a limited role in spreading the virus,
said Russell Viner, president of the Royal College of Paediatrics and Child Health in the U.K.
“We’ve always known that schools are good at transmitting bugs ...but the truth is
- from the evidence we have from multiple countries around the world -
that schools are not places that transmit Covid very well,”
Prof. Viner said.
Some research, however, indicates children may be carriers of the coronavirus just as much as adults,
and the researchers behind those findings suggest children are likely capable of spreading it, too.
An OECD survey of 1,370 teachers, principals and government officials in 59 countries found that 81% expected quarantine measures would be used in future outbreaks.
Only 13% said the entire school would close.