What's your criteria for a day off school/how ill do they have to be?!

[Justgivemeasoddingname]

DS 13 came home yesterday lunchtime with a head cold, sore throat, headache, blocked nose. Last night seemed a bit worse so I let him lie in this morning. He's been OK today but not done much, went out on his bike for 15 mins, read a book, played xbox and generally moaned but that's normal
My problem is he would always rather not go to school! He doesn't want to go tomorrow and I've told him I'll decide. The thing is, because he would rather be home and lounge around I think I should send him- it's only a cold after all, but is that too harsh? I appreciate he doesn't feel well but I'm not expecting him to run a marathon, and he is able to learn etc.
How do you decide??

Vomit
Temperature
Cough/cold if unwell in himself, awake in the night etc.
If he’s got a cold but otherwise bouncy he goes.
He’s 6 - I’ll get tougher as he gets older as well. He’s too little to feel poorly at school just yet. Fortunately he’s at a lovely independent school who don’t penalise children for being poorly, so no attendance rubbish you hear about sometimes.

If they aren't well enough tho walk the mile to primary school. (Then I still have to drag them out to get the others to the walking bus half way there. And the whole way there and back at home time coz th walking bus is only a morning thing)

The attendance obsession doesn’t worry me; if mine are unwell they stay off.

I see so many sent in unwell and it’s disgusting parenting imo. The child needs to be at home getting better and not spreading their germs around to the rest of the class.

There is always someone somewhere who justifies sending in their unwell child. Total horseshit and I don’t buy any of it.

I have no shame for going to work with a slightly sore throat, a cough and a stuffy nose. I can't stay away from an office job with indirect patient contact (non-clinical) because I feel sub-par. Yes, in an ideal world, we would all only have contact with other humans if we felt tip-top. But to take a day off because I am coughing and sneezing is quite frankly ridiculous. As I said, I used scrupulous hand hygiene, avoided patient contact, used tissues (frequent, fresh and discarded often), and didn't touch paperwork after coughing/sneezing unless I'd washed or gelled my hands (a study showed that hospital notes had more germs on them than some ward surfaces, if I recall ). I've done my best in an imperfect system.

It is an impossible system.

I read somewhere years ago, that in the 50s children were ill less but stayed home longer when they were ill. With an at home parent, more illnesses stayed confined.
Before antibiotics, I imagine people rested up with a what we consider minor for fear of what we now know are secondary infections.

My two (DS9 and DD6) would go into school moderately snotty and coughy with a standard cold type symptoms.

I always keep them off for at least 48 hours after v or d.

I would also keep them off for contagious illnesses like chickenpox.

Anything else I take a judgment depending on how they are feeling/behaving. If they are lethargic and not eating I keep them at home. A slightly raised temperature or bad cough but eating and bouncing around then I take them to school but am ready to pick them up if necessary.

They tend to have about 3 or 4 days off per school year. I'm not strict when they're off. I wouldn't take them out and about unless I really had to, but they're allowed to watch TV, lounge on the sofa, play on the computer, play with toys or go out in the garden if they feel up to it. Usually day 1 they just lounge and watch TV/nap. As they start to feel better they do more.