The Boston-area coronavirus wastewater tracker is showing that COVID levels are starting to plateau after the steep plunge following the omicron surge.

Both the south of Boston and north of the city COVID wastewater levels had plummeted more than 98% from the omicron peak in early January. Now the levels in the last week have been plateauing at low summer 2021 levels.

The region should expect that COVID will continue to spread at a low rate as the omicron subvariant circulates and as masks come off, according to infectious disease experts.

“This isn’t too surprising,” Boston University epidemiology professor Matthew Fox said of the wastewater plateau. “Rates go up really fast with omicron, then they come down really fast.