Chinese authorities have ordered three-and-a-half million residents of Beijing’s most populous district to undergo mass testing for COVID-19. The order set off a run on grocery stores, as residents feared they may soon suffer the same fate as Shanghai, where some 25 million people have been shut in their homes for weeks. Another 30 million people in Chinese cities outside Shanghai and Beijing also remain on lockdown. China recently reported its highest rates of community spread since the start of the pandemic, as it struggles to enforce its “zero-COVID” strategy.