Some of the places with the lowest rates of infections and deaths in this pandemic, like New Zealand and Singapore, have taken a “zero-COVID” approach to the virus. Think lockdowns, widespread testing, rigorous contact tracing, mandatory quarantines and restricted travel, even enforced by police. But the rise of delta is challenging the long-term sustainability of this approach. Many places are starting to accept that the virus can’t be completely eliminated. As The World’s Elana Gordon reports, that means moving toward relying on effective vaccines in combination with less intensive measures.