The rate of new coronavirus infections was plateauing in the United States Thursday -- a warning sign that has previously predicted new surges, even as data showed one in eight Americans are now fully vaccinated.
According to the Centers for Disease Control and Prevention, the latest 7-day average of new cases was 54,201 as of March 16, a level that has remained roughly consistent for the past week.
Cases were rising in fifteen states and territories, according to a tracker run by Johns Hopkins University, with a worrying cluster in the northeast including New Jersey, Connecticut, Rhode Island and Delaware.
Another serious spike was occurring in the midwestern state of Michigan where the average of new cases has more than doubled over the past month.
"Why the stall? Suspect B.1.1.7 is now starting to really have an effect," Ashish Jha, the dean of Brown University's School of Public Health wrote on Twitter.
B.1.1.7, better known as the UK variant, is both more transmissible and causes more severe disease.
Last week, CDC director Rochelle Walensky said the variant was on track to be the dominant strain in the US by the end of March or April.
At the same time, the country has been continuously escalating its immunization rate, which stands at over 2.1 million per day.
Some 40 million people or 12 percent of the total population are now fully vaccinated, and over 113 million shots have been administered in total.
Jha said he was heartened by the ever-increasing pace, but worried as some states were loosening public health restrictions too fast, such as mask mandates and capacity limits in restaurants and businesses.
"Am I sure we'll see cases rise? No, but worried," he said.
"Let's finish vaccinating high risk folks Then smartly relax public health measures."