A COVID-19 outbreak that has partially shut one of the world’s busiest container ports is heightening concerns that the rapid spread of the delta variant will lead to a repeat of last year’s shipping nightmares.

The Port of Los Angeles, which saw its volumes dip because of a June COVID-19 outbreak at the Yantian port in China, is bracing for another potential decline because of the latest shutdown at the Ningbo-Zhoushan port in China, a spokesman said. Anton Posner, chief executive officer of supply-chain management company Mercury Resources, said that many companies chartering ships are already adding COVID-19 contract clauses as insurance so they won’t have to pay for stranded ships.

It seemed as if things were just starting to calm down, "and we’re now into delta delays,” Emmanouil Xidias, partner at Ifchor North America LLC, said in a phone interview. "You’re going to have a secondary hit.”