From Chris Whitty at the Downing Street briefing yesterday: about 10% of London and about 4% of the rest of the UK are thought to have had Covid - so around three to three and a half million people. At a cost of probably 50,000 deaths. So we have a long way to go, in many respects, before we achieve herd immunity, with a resistant population of around 60-70%, plus any overshoot that takes place.