Hey guys quick covid question....

So my uncle visited my grandma yesterday for only 10 minutes (socially distanced just bc he always tries to protect her). And today his son (about 12 yrs old) woke up with a very slight fever and was fine a few hours after. No one else in their family is sick or have any symptoms. The son even took an at home covid test and it was negative.. but I’ve heard a lot of stories about at home tests giving false negatives.

Anyways, my uncle is vaccinated And boosted and so is everyone in his family. Do you guys think the chances of him being contagious and passing it to my grandma is slim if his son actually had covid?