Maybe we shouldn't be surprised that a vast gulf is opening up between Covid vaccination rates in the richest countries and the poorest. But still the numbers are shocking. While the UK has given 27% of its population a first dose, many nations have yet to inject a single arm. Hardtalk speaks to Dr Seth Berkley, head of Gavi, the Global Vaccine Alliance and key driver of the effort to ensure the whole world gets Covid protection. It is a great ambition; is it achievable?