POTTERING around her kitchen on the morning of 31 December, Kate Broderick scrolled through the headlines while she waited for her tea to brew. One story caught her eye: a mysterious outbreak of severe pneumonia in Wuhan, China. Nearly overnight, the number of cases seemed to explode. “I knew we didn’t have time to wait,” she says. A molecular geneticist at Inovio Pharmaceuticals in California, Broderick was poised for what came next. When Chinese officials published the genetic sequence of the new SARS-CoV-2 coronavirus causing the illness just two weeks after the first cases were reported to the World Health Organization, Broderick got to work. Within 3 hours, her team had a prototype vaccine ready for initial testing. It was an unprecedented turnaround, but a moment Broderick and many others had long seen coming. Making vaccines usually takes a decade or more between development, safety testing and manufacturing, says Seth Berkley, head of Gavi, an international group that promotes vaccine use around the world. With global confirmed cases of the new disease, covid-19, surging past 180,000 as this went to press, time is of the essence.