Containers full of frozen food and chemicals are piling up at China’s biggest port in Shanghai as a Covid lockdown in the city and compulsory virus testing means truckers can’t get to the docks to pick up boxes. A shortage of trucks to haul containers from the port is impeding the clearance of imports.

Shanghai is now the epicenter of China’s worst Covid outbreak in two years, with more than 21,000 cases reported last Thursday. The shortage of trucks is also hitting companies in the city, which have been able to continue working through the lockdown.