So far, Australia has been doing pretty well in the fight against COVID-19. Using a combination of social distancing, tight travel restrictions and contact tracing, the country has kept its death toll under 100 people and seems to be leveling off its new cases. It’s even managed to avoid closing schools. But despite the relatively minor impact the novel coronavirus has had on life in Australia, medical workers are still running low on masks, gloves and gowns.

“Suddenly it feels like a house of cards,” said Simon Quilty, senior staff specialist at Alice Springs Hospital in Australia’s Northern Territory. “We haven’t quite [run out of personal protective equipment], but we’ve come very close to it. We don’t even have the pandemic. If we do get a pandemic, we’re fucked.”

All around the world, whether hard-hit by the virus or not, countries are running low on crucial supplies. And while shortages are largely confined to disposable medical items for now — personal protective equipment (PPE), swabs, chemicals used for COVID-19 testing — experts say other shortages are likely. The spread of SARS-CoV-2 (the virus that causes COVID-19) is affecting the way we manufacture all sorts of products, and the way we get those products to where they’re needed. People who study these supply chains have seen problems coming for years. Now they’re scrambling to get ahead of the pandemic, before it ends up affecting even our ability to produce the vaccines we hope will stop the disease in its tracks.

“Up until a few weeks ago, I knew very little about the supply chain,” said Megan Ranney, a professor of emergency medicine at Brown University. “It always just worked. But I’ve learned a bunch, and it’s more fragile than we ever thought possible.” COVID-19 has forced her — and lots of other hospitalists around the country — to become supply chain experts on the fly.

A supply chain is a fancy term to describe how products get made and moved all around the globe. It’s a simple concept, but not a simple process. Supply chains aren’t a conveyor belt — they’re a ballet. And there are many, many ways this spectacular show can fall flat on its face. The production of a single item often involves multiple factories in several different countries and depends on speedy, reliable international shipping to get each piece to the right place at the right time — and then to the buyers exactly when they need it.

In fact, experts in both manufacturing and medicine have spent years warning of the risks a pandemic — or another major disaster — could cause to supply chains. In 2011, for instance, Quilty documented that the hospital where he worked at the time had less than a 30 days’ supply of penicillin and many other crucial pharmaceutical drugs. A 2017 paper by scientists with the Centers for Disease Control and Prevention pointed out that PPE supplies had run into problems during the 2009 H1N1 influenza pandemic and the 2014 Ebola virus epidemic, and warned that the system wasn’t prepared to handle a sudden increase in demand. Multiple reports have been published on how avian flu pandemics could disrupt everything from computer manufacturing to the global food supply.

“PPE is the canary in the coal mine,” Ranney said. She, and other experts, told me that right now, that’s the main place we’re seeing supply chains break down. But those same issues apply to damn near everything else we make and sell. The longer the pandemic goes on, the more products will be affected.

There are three big problems with the global supply chains, experts told me. First, the push toward lowest-cost production means a lot of cheap goods and cheap components of more valuable goods are made in places with low-cost labor. When those countries experience a pandemic outbreak — or when a pandemic interrupts transport from those countries — it creates a bottleneck.

Around half the world’s face masks came from China before the novel coronavirus pandemic began. The virus interrupted manufacturing there early on, Ranney said. Now, China can make masks again, but demand has jumped all over the world, and there are shipping delays. Several companies have told her to expect deliveries to take three or four weeks. In the meantime, she’s been left to sort through sketchy, back-alley PPE dealers, some of whom produce low-quality masks that either fall apart or don’t filter properly on testing. Other would-be suppliers have turned out to be basically the high-stakes equivalent of one of those “you’ve inherited $3,000,000!” email scams.

American manufacturing companies are starting to switch over production lines to make masks and other protective equipment here — but that’s not a quick process and presents its own complications. For example, the nonwoven textiles that N95 respirator masks use to filter out viruses have to be made on special machines. There are only a few of those machines in the whole world, said Julie Swann, professor of industrial and systems engineering at North Carolina State University. And you can’t just go buy a new one off the shelf. Her university is producing some of this material now. “But not at the volume you’d make at a large manufacturer,” she said.

The second problem is that a global pandemic causes sudden spikes in demand for certain products. Production is designed for steady demand with predictable increases and decreases. A big, unforeseen event, like a pandemic, throws everything out of whack, said Adegoke Oke, professor of supply chain management at Arizona State University’s school of business. Take our toilet paper woes. That supply chain didn’t account for sudden, nationwide increases in having to pee at home. It also didn’t anticipate every office in the nation suddenly holding it, indefinitely. You might think that the demand in one sector could be met by the excess from the other, but it doesn’t work that way. “The type of toilet paper you use in the office — the big rolls — are totally different from what you use at home,” Oke said. “They require different supply chains and different manufacturing lines.”

And when manufacturing capacity can’t keep up with a sudden surge in demand, there are no emergency backup supply closets to raid. That’s because of a popular and widespread business practice called “just in time” supply. Essentially, it means that businesses from hospitals to grocery stores keep only a small amount of supplies on hand at any given time — enough to get through a couple of weeks or a month. Just-in-time saves money on warehouse storage, energy and staffing, but it works only if the supplies can be produced and delivered when you need them. “It’s been very successful,” Oke said. “But at a time like this, the last thing you want is just-in-time.”

Finally, supply chains are also getting disrupted in some truly surprising ways — ripple effects that spread from one industry to another. Take the transportation of goods. Turns out, it’s pretty dependent on European tourism — 80 percent of the air cargo capacity across the Atlantic comes aboard passenger flights. When those all but stopped, it created a transportation bottleneck for manufacturing, said James Robinson, an independent consultant who spent 30 years working in vaccine manufacturing for companies like Merck. Airlines are turning their empty passenger jets into cargo flights, but that takes retrofitting and time and money — and it’s going to increase the cost of shipping, Robinson said.

Then there’s all the food being trashed in response to a pandemic that’s cleared grocery shelves nationwide. The same parallel but separate home and business supply chains that affect the toilet paper supply also affect food. What people eat in a restaurant or at school — and how much of it they eat — isn’t the same as what they eat at home. And the farmers who have typically supplied commercial kitchens don’t have the sales, marketing, packaging and transport networks in place to get their food where it’s needed. Fresh vegetables and milk have simply been thrown out. And that’s not to mention facilities’ closing when food industry workers are taken out by illness or migrant farm workers’ not being able to cross borders at future harvest times — things that researchers have long predicted could cause food shortages in the U.S. during a time of pandemic. “The food supply could be vulnerable,” Swann said. “As much as I don’t want to scare people.”

These supply chain issues can also create a weird sort of feedback loop: The virus increases demand for certain products, which jumbles supply chains for those products, which in turn hampers efforts to use those products to keep the virus in check. And that gives the virus time to beat up the economy even more.

Which is all to say that problems with the PPE supply could be only the beginning. As people like Robinson try to coordinate what will become an international effort to manufacture a COVID-19 vaccine in the months ahead, for example, they’re looking at what’s going on with products like PPE — knowing that the same things could happen to vaccines.

“A vaccine manufacturer like Sanofi might source several thousand ingredients to make a vaccine,” Robinson told me. “But each material is coming from factories with hundreds of sources, and those sources have sources.” Like the connection between holiday travel and international shipping, supply chains for vaccines can end in unexpected places — like a Chilean tree farm.

Robinson is vice chair of the scientific advisory committee for the Coalition for Epidemic Preparedness Innovations, an international organization that helps coordinate funding and research for vaccines against emerging infectious diseases. CEPI is involved in the development of 10 different coronavirus vaccines, and Robinson expects at least three of those will eventually make it to widespread use. One of these vaccines, though, uses an adjuvant — a substance to help strengthen the body’s immune response to a vaccine — that contains an oil extracted from the Quillaja saponaria Molina tree, common to Peru, Chile and Bolivia. The bark is harvested only between November and January each year, so this year’s harvest didn’t take the new coronavirus into account. There’s only so much of that adjuvant available until next year, Robinson said.

Other expected supply chain issues with vaccines are shaped by years of international trade patterns. For example, doses of vaccines are delivered in glass vials, and there’s been a global shortage of glass stretching back to at least 2015. The medical glass industry was just beginning to catch up with increased demand, Robinson said, and now, novel coronavirus vaccines will create additional pressure. Even if the vaccine is loaded into 10-dose vials, that’s still hundreds of millions of vials that will be needed, he told me. Janssen, a division of Johnson & Johnson, is developing a novel coronavirus vaccine that Robinson regards as one of the most promising. “[Janssen has] already preordered 250 million vials, and that might be all that’s out there,” he told me. “We’re trying to procure another 200 million.”

What it boils down to is that even the vaccine industry isn’t prepared for a sudden increase in demand on this scale — which would likely far outpace even the spikes associated with a bad flu season. “In 2009, H1N1 rapidly increased manufacturing and got up to 400 million doses in a year. But for a pandemic, we might need billions,” Robinson said.

The biggest thing experts are taking away from all this is the weakness of that just-in-time supply chain. “In lean terminology, inventory is waste because it’s supply you aren’t using,” Robinson said. But now, when demand is sharply rising, that inventory would be helpful — and so many industries are tied together that when one runs out of supply it affects the ability of other industries to keep functioning.

Production can be ramped up, and it is. But it takes time and investment — and it’s important to remember that those investments are a risk. We might need American-made masks now, but will we keep buying them after the threat of COVID-19 has passed? Or will we revert to just-in-time supply from cheaper factories overseas? History suggests the latter. During previous epidemics of influenza, Texas-based company Prestige Ameritech saw demand soar, Swann told me. But it proved to be a boom and bust. The company invested in new machines to meet demand during the 2009 H1N1 pandemic, Swann said. “And then they almost went out of business later because [the Texas company’s product] was a little more expensive than the ones from China,” she said. “We need to be willing to pay a little more during times of peace without crisis so we have supply available during crisis.”