As the coronavirus pandemic spreads throughout the United States, some health experts are warning that hospitals are not prepared to manage the anticipated number of patients, if there is a large spike in severe cases.

"If we have a large spike of cases -- no, American hospitals are not going to be able to handle it," said Dr. Ashish Jha, the director of the Harvard Global Health Institute.

It's unclear exactly how many people might need to be hospitalized, but doctors are trying to figure that out as healthcare systems prepare for what could be a large influx of patients.

Doing the math

CNN obtained one estimate presented to the American Hospital Association by Dr. James Lawler, at the University of Nebraska Medical Center on March 5 predicting that over the next two months, 4.8 million patients will be admitted to hospital because of coronavirus, including 1.9 million stays in the intensive care unit.

"This estimation is just that, an estimation," Lawler said in an emailed statement. "However it is based upon the best epidemiological modeling and opinion of experts in pandemics and respiratory viral disease. This estimation assumes no attempt to lessen the outbreak, so there is the potential for these numbers to be altered somewhat by following public health recommendations like social distancing, avoiding large gatherings and practicing good hand hygiene."

Dr. Eric Toner, a senior scholar at Johns Hopkins Center for Health Security, believes the need could even be even greater. Toner has been encouraging hospitals to prepare for a potential wave of coronavirus patients using numbers from a more familiar outbreak, an influenza pandemic.

The coronavirus is much more deadly than the flu, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, testified Wednesday during a hearing before the House Oversight and Reform Committee.

But he said the surge in patients is something the country has had experience within the health care system.

In the 2017 US Department of Health and Human Services Pandemic Influenza Plan, the government modeled what it thought could happen with a flu pandemic.

Using a hypothetical moderate to a very severe influenza pandemic, the plan estimated that with a moderate pandemic, 40 million people would need medical care, 1 million would need to be hospitalized and 200,000 would need intensive care. If the pandemic was very severe, 40 million would need medical care, but 9.6 million would need to be hospitalized and 2.9 million would need to be treated in an intensive care unit.

Toner said hospitals should get ready for a scenario similar to that of the 1918 Spanish flu, which left an estimated 500,000 people dead in the United States.

"I don't think that will happen everywhere. It probably won't happen in most places, but it will happen in some parts of this country."

Toner said no one really can predict where that may happen, but he said resources could be stretched in a way that may shock a lot of people where the cases spike.

"That is what they were experiencing in Northern Italy, where there were apparently not enough resources and people with respiratory failure are not getting on ventilators and they are rationing care," Toner said. "This is not in some dark ages medical care system, this is happening today in an advanced country with an excellent health care system."

Lawler's report estimates 4.8 million patients could be admitted to hospitals in the coronavirus pandemic -- but the US doesn't even have 1 million beds. According to the American Hospital Association, there are a total of 924,107 staffed beds across all the hospitals in the United States.

In recent years there has been a reduction in the overall number of hospitals, emergency rooms, and hospital beds, Toner said.

"Keep in mind though that this doesn't happen all at once," he said. Each community will have its own epidemic that will last 6 to 8 or 12 weeks, he said with a wave and peak that will then subside. So resources could be stretched in certain areas, but not in all areas at once.

Other equipment in short supply

Harvard's Jha said it's not just a shortage of hospital beds that is a concern. It's the additional equipment that medical staff needs to protect themselves and others from contracting the coronavirus. "Possibly a shortage of gloves, respirator masks and ventilators for people who develop pneumonia," Jha said. "And a shortage of doctors and nurses if they become ill."

Jha said if we do flatten the curve, and can keep the virus from spreading quickly, then hospitals will be OK.

"If we can spread those infections out over many weeks, and in fact, actually over many months, then yeah I think our hospitals can get there, but they're gonna have to start working now and getting prepared for what is going to be a lot of cases," Jha said.

"We did not consider a situation like this today," Dr. Robert Kadlec, an assistant secretary of Health and Human Services, told Congress this week. "We thought about vaccines. We thought about therapeutics. We never thought about respirators being our first and only line of defense for health care workers."

Officials with health care systems across the country say they are working hard to make sure they are as prepared as they can be.

Victor Giovanetti, the executive vice president for hospital operations at LifePoint Health -- which operates 88 hospitals in 29 states -- said that they regularly prepare for disasters like this. "We effectively prepare to handle infectious disease, tornadoes, floods, hurricanes and the like on a regular basis."

"Our teams are ready and actively working to not just support, but to take care of patients and to step up and do what needs to be done," Giovanetti said.

Some hospitals have begun to cut back on non-emergency procedures to prepare for expected coronavirus patients. Tufts Medical Center said Wednesday that it was beginning to progressively reduce the level of discretionary and elective clinical care for patients at its medical center and at Floating Hospital for Children to "conserve vital resources needed to provide optimal care to those who ultimately may need it most."

Giovanetti said that LifePoint Health has not canceled elective procedures or asked people to put off non-emergency appointments, but it does have a plan to make this kind of shift, if necessary.

"As we exist today we are in a position to take care of patients in our community and have excess capacity and presently have the staff we need to take care of the patients we are seeing," he said. "We don't know what will happen a week from now or in a month, but we have several contingency plans and are actively planning for scenarios involving a patient surge. Unfortunately, we have to prepare for these things every minute of every hour of every day."

Dallas-based Tenet Healthcare runs 65 hospitals and 475 outpatient centers and said that it has made preparations to both handle the expected surge in patients and to treat patients with other acute and life-threatening conditions.

"Our immediate priority will be to assess and prioritize patients, as we always do, focused on providing immediate care, as needed," said an emailed statement from a Tenet Healthcare spokesperson.

"We have developed dedicated triage areas, if needed, for potential Covid-19 patients where we can gather samples for analysis by the health department and accredited testing labs. We are prepared to provide the right care whether it requires hospitalization or whether the patient is one of the majority of cases that should be quarantined at home and treated on an outpatient basis."

Jha said hospitals should also take steps to postpone elective surgeries, implement social distancing measures, and ask employees who can work from home to do so.

"I think those are exactly the right thing we should be doing," Jha said. "What that does is really slows the rate of spread of that infection."