New COVID-19 hospitalizations in the U.S. are reaching levels not seen since last winter.

More than 29,000 weekly hospital admissions for COVID-19 were recorded last week – an increase of nearly 17% week over week – according to data from the Centers for Disease Control and Prevention.

The last time the U.S. reported new COVID-19 hospitalization admissions at a similar level was just under a year ago in January.

“COVID-19 activity remains elevated overall and is increasing in many areas,” the CDC said in a post on Friday. “Emergency department visits for COVID-19 are highest among infants and older adults.”

COVID-19 hospitalizations have been increasing for nearly two months. The trend is expected to continue as holiday travel and gatherings help the virus spread.

The CDC noted that it is monitoring JN.1, a new variant that quickly rose to the highest prevalence of any strain circulating in the U.S. It was responsible for more than 2 in 5 new infections in recent weeks, according to agency estimates.

JN.1, which is a close relative to BA.2.86, is the fastest growing variant in the U.S. However, the CDC assesses that “at this time, there is no evidence that JN.1 presents an increased risk to public health relative to other currently circulating variants.”

COVID-19 tests, treatments and vaccines are all expected to work on JN.1. So far, it doesn’t appear to cause more severe disease, but it does seem to have advantages over the other strains.

Low vaccination rates could also be giving the new strain a boost. The CDC recently warned that “millions of people may get sick in the next month or two, and low vaccination rates means more people will get more severe disease.”

About 19% of adults have rolled up their sleeves for the updated COVID-19 vaccine, according to national survey data. Public health officials have said that the uptake of the latest shot is too low.