You need a doctor's notice in Belgium if you're sick for more than one day. Which makes no sense, because e.g. when I was quiet sick two weeks ago, I knew it was nothing special and just had to sit it out at home, but I still had to go in and get my notice because I didn't work for three days in a row. Tested myself first (negative) because if I'd have been Covid-positive, I needed to go to an official test center or a pharmacist to register an official Covid positive test since you're (obviously) not allowed at a doctor's practice if you're positive.
I still think I'd like to know each time whether it's Covid or not, since I read that studies have proven that the more you get it, the worse it is for your body and organs, no? Or can the regular flu do the same amount of damage?