I'm yet another Russell Group academic mumsnetter and my university is currently planning for all large lectures (which is practically all lectures, courses with small lectures having long since been deemed unviable) to be online. Given that timetabling takes months at the best of times I doubt the university's going to change policy now, at least for the autumn term. If it does, though, and I am instructed to lecture in person, I think what I will do is to strongly advise my students not to attend, turn up in a respirator which I will not take off, and play my recorded videos on the projector. There are three reasons: the community, the students, myself.
The community: by the start of term a large proportion of our students (many of whom are only 17, and have only just become eligible to be vaccinated at all) will not be fully vaccinated. Our lecture theatres are overcrowded if we have anything like full turn out, and hardly ventilated, and there's very little that can be done about this in the available buildings (no windows, for a start). Case numbers are already starting to tick up again, and that's even before the schools have gone back. The idea that by the start of semester it'll be safe to lecture in person without expecting a resulting explosion of cases among students that will act as a centre of infection for the rest of the community seems frankly silly. Indeed it would be perfect conditions in which to select, and then spread, a vaccine-resistant mutant.
The students themselves: are not invulnerable. This is an age group which is quite susceptible to post-viral effects, even if they are not very likely to be hospitalised and die. And even if they do make a straightforward recovery, catching covid (or flu) is not harmless to them and their studies. Even missing a week of work during semester is very difficult to catch up from. Miss a month, and most can forget successfully completing the year. Moreover, students away from home, maybe for the first time, living in halls or shared accommodation with noone to look after them if they're ill? I wouldn't want a child of mine catching covid under those circumstances. I would not feel it was ethical to encourage students to congregate for in person lectures, and if my employer does it, I'll feel obliged to give contrary advice as an individual.
Myself: I've just spent a month making high quality video versions of my lectures, with hand-corrected captions, to a deadline that recently passed, because the university told me lectures would be online. As a result I haven't been able to take the annual leave I was due (well, nothing new there, only the reason varies). You think I'm now going to throw away that work and do the work of giving live lectures as well? Forget it. I'll take a book to my "play my video" in person sessions if I have to do them. (Giving live lectures to several hundred students is stressful, even when you are used to it. It doesn't just take the hour you do it for: it wipes you out for much longer.) An often-forgotten point is that immediately before the pandemic, we had the longest and most serious strike of academic staff in living memory. The level of goodwill and trust from lecturing staff to management is about zero.