The U.S. surpassed 12 million total cases Saturday after reporting steady rises in new infections over the past few weeks. It took the nation just 10 days to accumulate 1 million new infections between late October and early November, bringing it to more than 10 million total cases. It took six days after that to reach 11 million cases, and another six days to reach 12 million.

The situation is expected to get worse over the next couple of months due to cooling temperatures that will make it difficult for people to socialize outside, the reappearance of winter respiratory diseases and the pull many Americans feel to gather with friends and family over the holidays. As these factors collide, health experts are painting a “gloomy picture” for hospitals that are expected to be under immense strain throughout the nation.

Dr. Ali Mokdad is a professor of health metrics sciences and the chief strategy officer of population health at the Institute for Health Metrics and Evaluation (IHME), a research institute based at the University of Washington. IHME creates modeled projections for COVID-19 infections, deaths and hospitalizations based on current and anticipated measures taken to curb the spread of the pandemic.

The institute recently revised its models to predict that the number of COVID-19 deaths in the U.S. could rise from the more than 250,000 reported by mid-November to an estimated 471,000 by March 1—and that’s only if at least 40 states reimpose pandemic restrictions due to continued surges in new infections. If additional restrictions are not introduced, the country’s total COVID-19 death count could exceed 650,000 by March 1.

“We are heading in the wrong direction,” Mokdad told Newsweek, adding that the IHME’s models predict it “looks like a very dark couple of months” ahead for the U.S., with new infections likely to peak in mid-January and daily death counts expected to rise until mid-February.

“We are really facing a major challenge in this country with our hospitals,” Mokdad said. “What we are looking at in our projections are a gloomy picture in December and January. Short of hitting the brakes very hard in some states, unfortunately these cases will keep rising. Forty states have to hit the brakes—and hit them very hard.”

How the country handles Thanksgiving will be telling for how dire the situation becomes, Mokdad said. The Centers for Disease Control and Prevention (CDC) recently published a set of guidelines for Americans who do plan to visit with friends or family over the holiday, and states like California, Oregon and Washington announced travel advisories earlier this month discouraging travel and warning residents who do to quarantine for 14 days before visiting with others outside of their immediate families.

“We are so concerned about Thanksgiving, because we hear some defiance from people saying, ‘I want to celebrate,’” Mokdad said. “We are concerned about Thanksgiving being a super-spreader event, and it’s at the wrong time when we are already seeing an increase in cases.”

Mokdad told Newsweek that he is hopeful the U.S. will not get to a point where it is reporting 1 million new COVID-19 infections every two or three days because he said states will likely intervene before then. “States will not allow it,” he said. “They will impose strict mandates to stop this from happening.”

But Dr. Amesh Adalja, a senior scholar at Johns Hopkins University’s Center for Health Security, told Newsweek the U.S. might not even know when it reaches that point due to insufficient access to testing.

“We know we’re still undercounting cases,” Adalja said, adding that he estimates the actual number of daily infections in the U.S. is closer to 300,000 than the range of 150,000 to nearly 200,000 reported daily to the CDC the week before Thanksgiving. “I do think we’ll hit 1 million cases [every couple of days] before we actually report it. These viruses can spread, and you only get the tip of the iceberg when you look at testing.”

When the U.S. reported a significant infection surge in July and August, Mokdad noted, the country saw a rise in mask usage, which helped to flatten the curve a bit before its latest spike. But that was during the summer, when cold temperatures weren’t driving people inside and respiratory illnesses are not as common. Hospitals are typically busier during the winter months because frontline workers are caring for those who contract the flu, develop pneumonia and struggle with other illnesses that blossom amid the winter chill.

The easily transmissible novel coronavirus paired with the way it attacks patients differently—where some have no symptoms at all and others wind up in intensive care on ventilators—puts extra strain on the hospitals trying to prepare for new surges.

“Hospitals are getting close to the tipping point in many parts of the country,” Adalja said. “You’re already seeing that in places like El Paso, Utah, North and South Dakota, Wisconsin. You’re hearing about them needing to transfer patients and set up alternate care sites. All of that is telling you that some of these places are at their maximum capacity.”

A spokesperson for the American Hospital Association (AHA) told Newsweek that heath-care systems are preparing for expected surges by “employing a range of learned strategies” that health-care workers have shaped since the pandemic started so that they can better care for COVID and non-COVID patients, as well as protect those on the front lines. The experience that physicians and nurses gained by responding to coronavirus infections has led to “better outcomes” and shorter hospital stays for many patients, according to the AHA.

Even so, the country’s hospital systems aren’t approaching the winter months without concerns. “While hospitals can add beds, it is much harder to bring in additional health care workers, many of whom are justifiably experiencing a significant emotional and physical toll due to the impact of the pandemic,” the AHA’s Vice President for Quality and Patient Safety Policy Nancy Foster said in a statement shared with Newsweek. “Surges in rural areas are especially concerning since many rural hospitals have less capacity to expand the ability to care for patients and fewer resources to fall back on.”

Ensuring hospitals have adequate resources—including personal protective equipment and testing supplies—and funding is essential heading into the next few months, Foster said. “Everything possible must be done to ensure appropriate protections for our front line workers, which is why the AHA, along with the AMA [American Medical Association] and ANA [American Nurses Association], continue to urge the federal government and other stakeholders to use every lever available to increase the supply of PPE, testing supplies, and other items needed to win the battle against this virus,” she said.

“The funding hospitals and health systems have received to date, while helpful, is just a small fraction of what we estimate they will lose this year. We need further support and resources to ensure that we can continue to deliver the critical care that our patients and communities are depending on while also ensuring that we are prepared for the continuing challenges we face from this on-going pandemic,” Foster said.

Mokdad said several states could see “extreme stress” in their hospitals’ intensive care units over the coming months. Adalja said hospitals that become overwhelmed will have to shift into crisis mode and reassess their standards of care, which Mokdad said could result in expanding field hospitals or transferring patients to other medical facilities with greater bandwidths. Triaging patients would be a worst-case scenario for hospitals, Mokdad said.

“Short of our capacity to increase our resources and our staff, we’re going to start triaging patients, and then who’s going to be denied care? The elderly and the people with chronic conditions,” Mokdad said. “That’s not acceptable in the U.S. We shouldn’t allow the situation to reach that level, where our physicians and nurses are put in a position to decide who lives and who dies based on a protocol that every hospital has right now to triage patients.”

Mokdad compared a hypothetical dire hospital situation to one that could occur during wartime, when medical staff are forced to devote their time and resources to the patients who have a better chance at survival. He told Newsweek that he and other scientists are frustrated that the scenario he described was even possible for the richest democracy in the world, and that political divisions have prevented the country from taking a unified approach to managing the virus’s spread.

“In a time of peace, in a time where our country economically—aside from COVID-19—is doing extremely well, we don’t have an enemy outside except COVID-19. And we have all the resources we need,” Mokdad said. “Why are we allowing this to happen in the U.S.?”

Politics aside, Mokdad said the holidays pose a more immediate threat and point of frustration for scientists and health-care professionals. Though the CDC and several state leaders have encouraged Americans to celebrate virtually and avoid traveling or visiting loved ones outside of their family units, he said he is expecting the U.S. to report another big surge in the weeks after Thanksgiving.

“I don’t think Americans will do that, unfortunately,” Mokdad said of recommendations to avoid holiday gatherings. “Many people want to see their family and they’re tired of being isolated.”

Mokdad said he hopes Thanksgiving will serve as a wake-up call for Americans who may be considering celebrating Christmas, Hanukkah, Kwanzaa, New Year’s Eve and other holidays in late December.

“What happens at Thanksgiving will have an impact two weeks later,” Mokdad said. “I’m hoping after Thanksgiving we’ll see a rise of cases, and sometime between the holidays in December Americans will realize we have a bigger problem than we all have seen and expected.”

Correction 11/24 at 10:27 a.m. ET: The spelling of Dr. Amesh Adalja’s name has been corrected in this article.