Omicron, the highly contagious coronavirus variant sweeping across the country, is driving the daily American death toll higher than during last fall’s delta wave, with deaths likely to keep rising for days or even weeks.

The seven-day rolling average for daily new COVID-19 deaths in the U.S. has been climbing since mid-November, reaching 2,267 on Thursday and surpassing a September peak of 2,100 when delta was the dominant variant.

“Omicron will push us over a million deaths,” said Andrew Noymer, a public health professor at the University of California, Irvine. “That will cause a lot of soul searching. There will be a lot of discussion about what we could have done differently, how many of the deaths were preventable.”