Enraged by false reports on social media that polio drops had made their children ill, an unruly mob in Masho Khelhe, Pakistan, ransacked and then burnt a clinic where physicians vaccinated children against polio. The attack on 22 April came as long-festering suspicions and propaganda about the worldwide vaccination campaign boiled over across northern Pakistan in a heady mix of fear and wildfire rumor. Ben Farmer writes in the Telegraph that the hysteria of 22 April marked a worrying setback for a campaign which had been on the cusp of eradicating what was once a worldwide scourge, but has faltered. The scale of last month’s panic highlighted how divisive the vaccination program remains to some, despite years of public education, and also how it continues to be used as a focus of extremist propaganda. Anti-vaccine disinformation on social media has made the situation worse, officials say. They are particularly worried how the suspicion appeared to have spread from the illiterate rural poor and even gripped middle class families.