How long is Covid infectious for?

[KnowlWay]

It’s ‘ripping through’ the key worker kids at my DS’s school. Teacher and TA tested positive last week. If they return on 8th are they still infectious? My DH says the guidance says no but the new variant takes longer? Any scientific evidence helpful.

The isolation period is still 10 days from first symptoms although you would stay off if you still felt unwell or had a temperature.

Thanks. I really meant how long could it be contagious for. I know the ten days is recommended but is it very likely to be more?

I have covid atm. Test and trace told me that if i had a high temp or runny nose (there were some other symptoms too but I can't remember) at the end of the 10 days I might be still contagious and my isolation would be extended.