Vaccine researchers are preparing for Disease X

LAST YEAR the World Health Organisation published a plan to accelerate research into pathogens that could cause public-health emergencies. One priority was the bafflingly named "Disease X". The X stands for unexpected, and represents concern that the next big epidemic might be caused by something currently unknown. Preparing for such an eventuality is challenging, but not impossible. That, at least, is the view of the Coalition for Epidemic Preparedness Innovations (CEPI), a charity in Oslo, Nor...