Visiting family w/ nb who's child had a bad fever a week ago?

Katrice

So I have a newborn (3 weeks old) and we have family that wants to visit this upcoming weekend. The only thing is about a week ago one of their kids had a bad fever over 103 and they have 3 other kids. Do you think it's safe for them to visit? Or is it too risky that one of the other kids or the parents could be contagious?