But there has been a study showing that a booster dose does increase antibodies - and considerably. So it would make sense to offer a third dose to those age groups where two doses are not preventing hospitalisation sufficiently, definitely over 80, probably over 70 and maybe younger age groups. I agree evidence of waning immunity is not conclusive.
The interesting twitter modelling thread suggests that mask wearing and continued working from home would make a big difference. Most of us have been talking about measures or mitigations, not lockdowns, when discussing the data.
The other elephant in the room is the risk that the flu jab will be less effective this year - but masks and working from home also impact on flu to some extent. The NHS really needs there not to be a flu epidemic this year so that waiting lists dont increase to the 15 million considered possible, normal winter pressures seem to be overlooked in the modelling.
All young people have certainly not already been infected with covid - . an attack rate of, was it 76% in the twitter thread, still leaves quite a number to be infected. Hopefully the rest have some protection from vaccination but saying they are "as safe as houses" is an assumption not supported by the data.
A friend's teenage grandchildren were infected recently, shortly after one returned to school. Both seem to be doing well but they probably have had a single vaccine each, an anecdote to confirm the fallacy.