Last year my son went to school for the first time and came back with a ton of things from the regular cold to fifth disease (slapped cheek syndrome). Just super glad that it never went to my youngest. I think he missed like 6 days total because you have to be fever free for 24 hours.. so he had to automatically miss 2 days.
Eh it happens, last year my kids came down with hand foot and mouth. My middle schooler missed 2 weeks of school because of it. It sucked but chances are the kid that passed it to my 8 year old didn't even have symptoms, the only reason we knew my 8 year old brought it home is because she had a fever and mild sore throat for 2 days then was fine and then her siblings came down with the same fever severe sore throats and blisters.