By 15 February, the NHS had vaccinated the top four most at risk groups – groups that have accounted for around 88% of COVID-19 deaths and about 55% of hospitalisations. The UK’s four Chief Medical Officers say that you get “substantial protection within 2-3 weeks of vaccination”, which takes us to 8 March. So upon what evidence is your department relying in order to recommend that masks in classrooms are today necessary – rather than “nonsensical” – now that the four most vulnerable groups have “substantial ­protection”?