My tiny experience.
2 weeks ago, 30.10 a classmate of my daughter stayed some hours at our home (60 m2 apartment) after school with my daughter and wife. When i arrived i basically said hello and good bye and the classmate left.
On monday morning 2.11, the mother of the classmate called and told that her daughter got positive test and mild symptoms (on friday she do not had any visible symptoms). It seems she got it week ago in sunday bible school at the church, where the teacher had probably also non-tested COVID at that time.
Wife called our family doctor, she told us to stay home. Although my close contact was about less than 5 minutes, i stayed at home. Of course, the teacher sent my daughter and other classmates also to home.
On monday, 9.11 we our family did the tests, all were negative. At the moment all the other classmates too (minus the original positive one).
So it seems, that on right conditions something else is needed to infect somebody, if 5 days at school and 2 hours at home with pretty close contact is not enough.