Seen and not herd

摘要

AT FIRST SIGHT, the decision by America's Food and Drug Administration to pause the roll-out of the covid-19 vaccine from Johnson & Johnson is a comparable setback to that in Europe over the Oxford-AstraZeneca jab. In both cases the worry is about whether there is a link with blood clots. And in both cases, such clots are extremely rare, meaning that in most circumstances not getting a shot is a far higher risk to health. Yet whereas in Europe the AstraZeneca blow came at a time when countries were struggling to supply vaccines, America is now awash with them. So the main impact in America is less on supply than on people's wariness about getting vaccinated at all. The country is close to delivering jabs to almost all who want them. Unfortunately, only seven in ten Americans are interested. To suppress the coronavirus effectively, 70% or more of the entire population must be vaccinated-a high bar, given that the vaccine is not administered to those under 16. Anything that reduces take-up makes such herd immunity even harder to attain.