A stampede for an unproven “cure” for Covid-19 is clearing the pharmacy shelves of a medicine that is vital for up to 5 million people around the world suffering from lupus, as countries bow to populist pressure and abandon the trials that would show whether hydroxychloroquine works against coronavirus infection. Both Italy and France have said doctors can now prescribe hydroxychloroquine – a less toxic version of the malaria drug chloroquine – even though there is no robust evidence to prove that it is effective against Covid-19. Popular pressure for access to the drug has been ramped up by pronouncements...