Masks are a rarity now on streets and trains. We don’t leave empty seats in theatres or limit how many people browse in our shops. It seems like it’s all over – but Prof Sir Jeremy Farrar, director of Wellcome, once a key member of the government’s scientific advisory body Sage and an enormously influential figure in global health, says the Covid pandemic could still have unpleasant surprises in store. Farrar is not a doom-monger. But from where he is sitting, with long experience of epidemics from flu to Sars to Ebola, we are still in a risky place. We...