Coronavirus China, South Korea, Germany: Cities back in lockdown

Everyone who hasn’t had COVID-19 is tinder for a fresh pandemic eruption. And doubts persist that those who have had it remain immune for long. Which means herd immunity – the level of resistance within a community necessary to stifle any outbreak – remains an intangible dream. “Herd immunity is not this magical number where once you reach that point nobody else gets infected,” La Jolla Institute for Immunology in California immunologist Shane Crotty told Popular Science. “It would no longer be a full-blown epidemic once you get to herd immunity, [but] the virus would still spread, it would still infect people, it would still kill people. It would just be a less common event.”