Around the country, the average number of new COVID cases has been relatively stable. But that's not the case everywhere, especially out West in states where vaccination rates are relatively high. So what's behind the surge?
The short answer is experts and doctors don't know exactly what is driving this surge, but one thing they do know is: It is likely to get worse before it gets better.
By this point in the COVID pandemic, health officials had hoped the country would be turning a corner.
"If you'd asked me last June, July, with effective vaccines widely available, if we'd be in this kind of shape in the fall, it certainly would not have been my expectation," said Dr. Jonathan Samet, dean of the Colorado School of Public Health.
Across the U.S. new COVID infections have been relatively flat.
Places like Florida, Georgia and Mississippi are seeing recent drops in new cases.
But out West, in states with relatively high vaccination rates, it's a different story.
Colorado, California and now New Mexico, where the vaccination rate is 73%, are all seeing COVID surges.
Even in Vermont, where 81% of the population has at least one vaccination dose, cases are up 51%. One Vermont college blames Halloween parties that resulted in dozens of new infections.
In Colorado, where 62% of residents are vaccinated, health experts are not sure what's behind the surge. It could be that colder weather is driving people indoors and in closer contact. Fewer people are wearing masks as pandemic fatigue sets in. But those things are true in other states, and there seems to be no smoking gun.
"Our whole team has worked as hard as we can to see if there's one particular factor that we can point to and say yes, this is it. We have failed to do so," said Dr. Samet.
And with people about to travel for Thanksgiving and other holiday gatherings, experts warn the surges could get worse.
"The holidays are a time we get together of course and we share a lot of things at those moments, including viruses, and that is a worry," said Dr. Samet.
To help flatten the spikes, health officials are urging people to do two things:
"Vaccinate, vaccinate, vaccinate," said Dr. Samet. "The other is people don't need a mask mandate to wear a mask."
This current surge means some hospitals are running out of intensive care beds — which means for people suffering from heart attacks and strokes, urgent care is harder to get. Health care providers in Colorado told Newsy that 80% of the people hospitalized for COVID infections are unvaccinated.