So, I have a sim with flu, Antonio Monti. Right now I played with David Ottomas' household, who called Antonio, and during this phone call, I got the pop up with the message that Antonio is healthy again. I mean, good news for him, but I wonder, is this normal or a bug? I got the message not in his household.

It's normal. It would also, alas, be normal for flu to spread by phone. When a phone call happens, the sim on the other end of the line is invisibly on the lot in order to interact. This is why it can be iffy to save with a sim on the phone, and why sometimes sims who have called will suddenly appear on the lot afterward.

Yeah but I never loaded the premade neighbourhood in the first place? Basically I want to be making a towny-free neighbourhood.

Thanks for the quick answer. I never save with Sims on the phone. I'm just glad that in this case that it didn't spread like this.