Top health officials at the Centers for Disease Control and Prevention (CDC) are warning that the Omicron variant of SARS-CoV-2, the virus that causes COVID-19, could peak in a huge U.S. wave as soon as January.

Using new modeling for the spread of the variant, the CDC said Tuesday the prevalence of Omicron has spiked sevenfold in just one week.

“The CDC briefing Tuesday detailed two scenarios for how the omicron variant may spread through the country,” The Washington Post reported. “The worst-case scenario has spooked top health officials, who fear that a fresh wave, layered on top of delta and influenza cases in what one described as ‘a triple whammy,’ could overwhelm health systems and devastate communities, particularly those with low vaccination rates.”