Ship congestion outside the busiest U.S. gateway for trade held steady over the past week, as ports from China to Germany battle with COVID-19 outbreaks and other constraints on their capacity to keep containers moving across the global economy.

A total of 13 container ships were anchored awaiting entry into the adjacent ports of L.A.-Long Beach as of Tuesday, compared with 12 a week earlier, according to officials who monitor marine traffic in San Pedro Bay. The bottleneck has persisted since late last year, peaking around 40 vessels in early February.

Another 13 container carriers are scheduled to arrive over the next three days, with five of those expected to drop anchor and join the line.

The average wait for berth space was 5.7 days, compared with 4.6 in early June, according to L.A. port figures. That number peaked around eight days in April.

Earlier on Wednesday, Yantian International Container Terminals said all berths at the port of Yantian, part the Port of Shenzhen in southern China, will be fully operational on Thursday after a virus situation was brought under control.

Earlier this month, A.P. Moller-Maersk A/S, the world’s No. 1 container carrier, said it was omitting stops at the Port of Hamburg because of “high yard density and exceptional waiting time” for its vessels.