The city of Beijing rode out the pandemic for almost three years, crushing Covid-19 outbreaks before the virus could overwhelm it. When dozens of cases flared in June 2020, the head of the Chinese capital’s Communist Party committee vowed to take “the most resolute, decisive and stringent measures to block transmission and control the situation”. The city’s defences held again in the spring when targeted measures such as localised quarantines helped it avoid a sweeping lockdown such as the one that immobilised Shanghai for eight weeks. Beijing’s party secretary, Cai Qi, a long-time ally of President Xi Jinping, was rewarded...