Have we reached herd immunity?

When the Office for National Statistics released the last antibody survey a fortnight ago, the results were underwhelming. After watching prevalence in the population shoot upwards for months, the figure had plateaued at 55 per cent. There were several reasons suggested for the stall, including the move to giving second doses and difficulties detecting fading antibodies (which the ONS is quick to point out does not necessarily mean a person no longer has immunity).