to be off school for longer than people who have a vaccination on average. and therefore since virtually any child unvaccinated is likely to get an infection at some point between 12 15, that is the correct comparison, not against nothing. and that s a really key point. president biden is asking world leaders to pledge to vaccinate 70% of the world s population against covid 19 by september next year. at a virtual summit, he said america would buy an additional 500 million doses of the pfizer vaccine to donate to poor countries, but research shows that richer nations still have a surplus of doses, some of which are reaching their expiry date. 0ur health editor hugh pym has more details. wealthier nations are pushing on with boosterjabs, but it s a different story in low income countries in africa and around the world, where vaccination rates are much lower. that divergence has been criticised