Earlier this month, the top officials at Massachusetts General Hospital in Boston were modeling scenarios for a possible coronavirus pandemic.

The emergency response team was meeting daily. The staff were receiving accelerated training on how to safely put on and remove protective equipment. The hospital even had a backup plan — an "Indiana Jones-style" secret warehouse stocked with medical supplies — meant to buffer supply chain gaps at the peak of an outbreak.

Now, three weeks later, the peak has not yet arrived, and the hospital is already being pushed to the brink.

The facility is digging into its emergency stockpile for crucial supplies — goggles, antiseptic wipes, specialized N95 masks — that were designed to last through the worst two weeks of the crisis. At least 41 staffers have contracted the virus. Arrangements are being made to repurpose recovery rooms and cardiac care units into intensive care beds. And hospital executives are scrambling to buy ventilators and obtain additional testing swabs.

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"Almost everything in this outbreak has come faster than we were expecting," Dr. Paul Biddinger, Mass General's chief of emergency preparedness, told NBC News on Monday.

"We have best-case and worst-case scenarios," Biddinger said. "I would say this is following our worst-case scenario in terms of how fast this is evolving. ... And that's not good."

Perhaps nothing illustrates that more clearly than the pace of the pandemic's mounting death toll. When NBC News first visited Mass General on March 2, there was a hush in the room when Erica Shenoy, associate chief of the infection control unit, announced at the Hospital Incident Command meeting: "On Saturday, the first death was reported in the United States."

Today, the death total is more than 700. Mass General has 29 confirmed patients with COVID-19, the disease caused by the coronavirus, 11 of them in the intensive care unit. Some 110 others were awaiting coronavirus test results.

In the weeks since NBC News visited Mass General, the number of cases nationally has spiked to more than 54,000, including 1,838 in Massachusetts. The medical community has been trying to call attention to nationwide shortages of crucial equipment like ventilators and masks, a concern echoed by the majority of health care workers from 40 states who responded to an NBC News survey last week. Biddinger warns it is only the beginning.

"We think we are still several weeks away from the potential peak of the outbreak," Biddinger said. "And obviously, we have to pace ourselves to get through this."

But the hospital is quickly filling. It normally has 150 critical care beds, Biddinger said, but a surge effort can bring that to 300. Any space with oxygen and suction machines — from anesthesia recovery rooms to endoscopy spaces — is a candidate to be repurposed as an intensive care bed.

The hospital is adopting unprecedented measures, Biddinger said, including canceling elective admissions, locking down entrances and mandating that staff wear masks everywhere in the hospital.

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The space strains are a recent development. The shortage of personal protective equipment, or PPE, is not.

"I would say our supply chain is tenuous," Biddinger said. "We are monitoring every single delivery."

Mass General was running low on N95 respirator masks even before the facility took in its first COVID-19 case. By early March, workers were waiting for shipments that never came, totaling just one significant delivery in five weeks, according to the hospital. It got to the point that Mass General had to borrow masks from other hospitals to avoid breaking into its emergency reserves, said Ed Raeke, the hospital's director of materials and management.

"I am not comfortable at all with the levels that we have on hand," Raeke told NBC News three weeks ago during a tour of the stockpile.

Back then, the hospital predicted that the supplies would get it through the worst two weeks. But Mass General has already had to tap into the stockpile, and Raeke has had to establish a secondary cache to create a buffer for the most challenging times, which he expects are ahead.

"We quickly realized that a two-week backup was not enough, and our central supply team has done an amazing job bringing in the PPE and clinical products needed for the treatment of COVID-19 patients," Raeke said. "Supply is certainly tight, but we are managing it as best we can through extreme inventory controls and conservation practices."

Another concern now is ventilators — the breathing devices used to treat patients undergoing respiratory failure. The hospital typically has 150 ventilators on hand. It is trying to buy and rent more, Biddinger said, and has identified 200 additional machines to bring on board.

The ventilator numbers are a nationwide concern, sparking deliberations among state officials and hospitals as to how to determine which patients would get lifesaving care in a potential shortfall, NBC News reported last week.

Through the state health department, Mass General has requested ventilators from the federal government, Biddinger said, but the hospital has not received anything yet. He hopes to avoid having to put two people on the same ventilator — a last-resort process that requires deeply sedating or paralyzing patients. But he is preparing for it, just as he is preparing for a host of worst-case scenarios, which are calculated and debated in the hospital's incident command system, an emergency response team of leaders from across the hospital.

The drug supply chain has been a point of continued concern. The hospital is constantly monitoring — and in some cases restricting — medicines that may help treat the effects of COVID-19. As researchers race to identify effective COVID-19 treatments, the promise of new drugs can lead to shortages and backlogs.

One such treatment is metered-dose albuterol, an asthma drug being used to treat respiratory complications due to COVID-19. Another is hydroxychloroquine, an anti-malaria drug that President Donald Trump described as "very, very encouraging" in early tests, though top experts caution that the evidence is anecdotal so far and further study is needed.

"We just need to use those products in the proper way and for the proper patients," said Chris Fortier, chief pharmacy officer at Mass General. "Not just saying: 'Well, I might have COVID symptoms. I need to get put on albuterol.' That's really not where we need to go. We need to continue to utilize these for patients that need them most."

Mass General has had to restrict use of both drugs, Fortier said. Those kinds of decisions require hour-by-hour, day-by-day calculations, with a changing cast of potentially lifesaving drugs to watch.

"Working on these shortages and determining what we can get from supply can be pretty exhausting and pretty stressful," Fortier said. "But we're committed to it. And we'll continue to ensure that if we can get these medications, we can get them for our patients."

But despite extensive planning, unexpected challenges are popping up. For example, nobody at Mass General expected testing swabs to become a commodity in short supply, Biddinger said. But with pushes for expanded COVID-19 testing, he said, the hospital has been forced to pull swabs from research labs at the hospital and across Harvard University.

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Mass General's president, Dr. Peter Slavin, has called for "a Manhattan Project" to combat the epidemic — a reference to the World War II-era effort that engaged scientists, academics, industry, the military and government and led to the creation of the atomic bomb.

In the meantime, community residents are stepping up to help, Biddinger said, by donating personal protective equipment and even trying to print supplies with 3D printers.

Biddinger worries that the timeline for reinforcements is not moving fast enough.

"I can't stress enough that the time horizon is short," Biddinger said. "We need these things to happen within the next few weeks, not the next six months."

The hospital is also feeling a strain due to the more than three dozen staffers who have come down the virus. Some of the workers caught the illness from the community, Biddinger said, but the uncertainty surrounding transmission makes the hospital all the more worried about the shortages of personal protective equipment.

"I think it's a challenging time," Biddinger said. "There's no question. But it's also a time that I've never been prouder to be part of this hospital."

In a hospital strapped for resources, workers are digging deep. Some staff members have worked multiple seven-day weeks since January, according to the hospital. The full hospital staff — nurses, physicians, janitorial, food service alike — is showing up to work, Biddinger said, and even supporting each other with child care and food delivery.

"It's not to say people aren't tired," Biddinger said. "It's not to say people aren't scared. And it's not to say that, you know, people are wondering how long they can go. But I have yet to hear a single person say: 'I can't get through this. I'm not gonna make it all the way.' I think people are just putting their heads down and doing what they need to do."