Covid-19 cases of the delta and omicron variants are surging in many parts of the United States. But as Covid-19 cases rise, flu cases are also starting to increase, and experts are concerned about the impact this triple whammy may have on hospitals in the coming months.

The omicron variant: The 'good,' 'bad,' and 'ugly' scenarios

Covid-19 cases on the rise

As of Wednesday, the United States is averaging 119,888 new Covid-19 cases per day, according to Johns Hopkins University—a number that's roughly 50% higher than it was a month ago.

The country is also averaging 1,261 Covid-19 deaths per day—a 5% increase over the past month—and 67,306 people are hospitalized with Covid-19, according to HHS, a 43% increase over the past month.

In addition, experts from Harvard Medical School believe the proportion of omicron cases is likely being undercounted because the variant is moving faster than surveillance can track it.

"Our delta surge is ongoing and, in fact, accelerating. And on top of that, we're going to add an omicron surge," said Jacob Lemieux, who monitors variants as part of a research collaboration with Harvard.

"That's alarming, because our hospitals are already filling up. Staff are fatigued," which leaves limited capacity for a Covid-19 surge "from an omicron wave superimposed on a delta surge," Lemieux added.

On Thursday, President Joe Biden warned Americans that omicron is "here now and it's spreading and it's going to increase. We are looking at a winter of severe illness and death for the unvaccinated—for themselves, their families, and the hospitals they'll soon overwhelm."

And Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said Thursday he believes omicron "will assume a dominant role very soon, I would imagine within a period of a few weeks to as we go into January."

Lori Tremmel Freeman, CEO of the National Association of County and City Health Officials, said modeling data, alongside data from Europe, shows that Covid-19 cases from omicron have the potential to double every two days.

"That modeling implies that sometime in January, we will be at a different stage of recognizing omicron, maybe as even a predominant virus. However, we still are learning about the severity, transmissibility," Freeman said.

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On Wednesday, the United Kingdom recorded the highest number of new Covid-19 cases it's seen since the start of the pandemic, and the CMO for England warned that things are likely to get worse.

"The data out of the U.K. [is] quite alarming at this point" and is a sign of what's to come in the United States, said Bronwyn MacInnis, director of pathogen genomic surveillance at the Broad Institute of MIT and Harvard.

The 'perfect storm' of omicron, delta, and influenza

Meanwhile, as Covid-19 cases rise, flu cases are increasing as well. According to CDC, 841 people were hospitalized with influenza in the first week of December, an increase from 496 the week before.

According to Freeman, there is a growing concern that omicron cases, delta cases, and flu cases will all rise and potentially overwhelm health systems this winter.

"It's the combination. It's kind of the perfect storm of public health impacts here with delta already impacting many areas of the country and jurisdictions," Freeman said. "We don't want to overwhelm systems more."

Manish Patel, team lead for the influenza prevention and control team at CDC, said flu activity is unpredictable.

Last flu season, the United States "had no influenza activity … and minimal activity globally in the Southern Hemisphere or the Northern Hemisphere," Patel said. "And this really has not happened before since we've had surveillance for influenza. The jury is still out on reasons why that hasn't happened." (Ungar/Johnson, Associated Press, 12/16; Frazier, Axios, 12/16; Howard, CNN, 12/15; Sullivan, The Hill, 12/16)