I'm a teacher. If I've got this right, I will have to self isolate for 14 days if anyone in my household gets a cough. I can't even go back early if I get a negative test, because of the incubation period. I'm not sure if I can go back if I have no symptoms and the household member tests negative? It's pretty unclear.
So, I see 2 options.
Option 1: Teachers follow the self isolation guidelines. For me, I estimate that will probably mean 6 weeks absence between now and Easter and I am not a special case. That's roughly a quarter of my time in self-isolation, and I am not basing this on anyone in my household actually HAVING Covid. This option means we will probably be trying to run on at most 75% of our staff at all times. I'm not sure how doable this is.
Option 2: Teachers might self isolate if they themselves have symptoms, but choose to lie about household members having them, and go in anyway. We MIGHT get away with this, but obviously, it will contribute to the risk of outbreaks in schools. If Covid cases do increase, this will really add to it, and if there is an outbreak in the area, it's likely to mean more schools shutting down completely.
Ideally, I'd like to see some way of using the 25% who are self-isolating, but quite possible perfectly well enough to work, in providing better quality out of school learning. I think we should be planning for high levels of self-isolation, because whilst we don't know how Covid is going to act over winter, we can bloody well figure out what all the other usual viruses will do and what levels of absence they will cause.
Which brings me to my last point - Why hasn't someone already calculated how much teacher absence is likely to be caused through self-isolation of normal viruses? It should be within our capacity. Someone could use school records to see what proportion of days off are caused by what types of illness. It wouldn't count all the students who come in with colds who now won't be, but it would work as a best case scenario and we could plan around that (as opposed to my back of a fag packet calculations above).