Zou Dehu had been a bartender in Ningxia in northwestern China before he left town after he got into a fight with his father. Now more than eight months later, he’s in Shanghai and working as a delivery man. Restrictions on movements because of Covid-19 have forced the city to rely heavily on the work of delivery services. But the challenges of operating amid a pandemic, and fears about the economic damage it has created, now have Zou worrying about what lies ahead.