The omicron variant is starting to loosen its grip on the U.S. Northeast, but experts warn that it will take more time for the latest wave of COVID-19 to recede nationwide.

The strain’s fast surge and swift descent in one of the most populous parts of the U.S. echoes its trajectory in areas of Europe and South Africa, where infections skyrocketed only to come back down nearly as quickly. That’s raised hopes that while omicron has at times seemed like a replay of the worst days of the early pandemic, it will soon ebb.

However, the shape of the omicron wave may look different in various parts of the U.S., depending on vaccination rates and hospital capacity in those areas. While omicron has been milder than other variants, it has strained health care providers across the country, and infections in children have been higher this time around.

Nationally, the omicron wave could peak as early as this week, according to projections from the Institute of Health Metrics and Evaluation at the University of Washington. Still, states where omicron’s spread came later will see a delayed peak, forecasters say.

“Omicron is coming down as fast as it went up,” said Ali Mokdad, a professor at IHME and chief strategy officer for population health at the University of Washington. “We are going to go through a couple more weeks that are very difficult on our hospitals, but come mid-february, March, we should be in a very good position.”

But low U.S. vaccination rates in certain regions have made some experts worry that the country might not bounce back quite so quickly from omicron. About 80% of Americans age 5 and older have had at least one dose of the vaccine, according to the Centers for Disease Control and Prevention. But some states — including Idaho, Wyoming and Louisiana — are struggling to get above 60%.