Governments cannot openly admit that the "controlled easing” of COVID-19 lockdowns in fact means controlled progress toward so-called herd immunity to the virus. Because there is currently no COVID-19 vaccine, governments have had to find other ways to prevent “excess deaths.” Most have opted for lockdowns, which remove entire populations from the path of the virus and thus deprive it of hosts. But this strategy has a terrible weakness: governments cannot keep their populations locked down until a vaccine arrives. Apart from anything else, the economic cost would be unthinkable. So, they have to ease the lockdown gradually. By Robert Skidelsky