COVID-19 case clusters offer lessons and warnings for reopening

That wasn’t the only cluster that put the brakes on South Korea’s reopening plans. Soon more clusters popped up in an online retail center, a theme park, a table tennis club and a handful of churches. Other countries should expect similar starts and stops upon relaxing stay-at-home rules. “Reopening is not a one-way street, and we may need to make a U-turn,” says Andrew Noymer, an epidemiologist at the University of California, Irvine.