BEIJING/SINGAPORE—Congestion off China’s top two container ports Shanghai and Ningbo is worsening following the shutdown of a container terminal in Ningbo where a COVID-19 case was detected this week. Tighter restrictions to fight China’s latest coronavirus outbreak are starting to hit more parts of the economy. The highly transmissible Delta variant has been detected in more than a dozen cities since late July. Forty container vessels were waiting at the outer Zhoushan anchorage on Thursday, up from 30 on Aug. 10 when a worker at the Meidong container terminal tested positive for COVID-19, data tracked by Refinitiv showed. Meidong terminal has suspended all operations since early Wednesday, while other terminals in Ningbo imposed restrictions limiting the number of people and cargo entering port areas. Shipping company CMA CGM put out a note on Thursday saying that some vessels will be re-routed to Shanghai or skip port calls at Ningbo. Hapag-Lloyd …