(Bloomberg) — In Rome, the first signs of change came from overhead. Shortly before cocktail hour on Monday, the thrum-thrum-thrum of a helicopter could be heard above the winding lanes of the 2,000-year-old historic center. The police were keeping an eye on the Trastevere neighborhood, where smoke billowed from the windows of a jail as inmates rioted, protesting cramped conditions that put them at risk of coronavirus infection.About the same time, the stock market was opening in New York, ushering in a week that would become the worst rout in more than three decades. A few hours later, Italian Prime Minister Giuseppe Conte gathered journalists for a televised, prime-time press conference. Rules that only 48 hours earlier had been imposed on Milan, Venice and other cities in the north—travel was restricted, schools were shut, and even the opera was called off—would be extended nationwide. The world’s eighth biggest economy, with more than 60 million inhabitants, entered virtual quarantine. It was like flicking a switch. In just days, a Western democracy went from Aperol Spritz to lockdown, as the outbreak spread from a northern crisis to a national one, now with more than 15,000 known infections and more than 1,000 deaths, second only to China.Read More: Coronavirus Can Live in Patients for Five Weeks After ContagionFor those lucky enough not to be living through the Italian lockdown, pay attention: What’s happening in Milan, Florence and Rome offers a likely preview of what’s coming to New York, London or Paris in a week or two. Consider this our letter to you from Italy, written from the seclusion of our couches and dining room tables, with a taste of what you should expect. Whether it’s shuttered shops, civil unrest, or the coronavirus itself, it will be difficult to avoid the trauma Italy has experienced in the past three weeks. President Donald Trump blamed the outbreak on a “foreign” virus Wednesday when he announced restrictions on European travel to the U.S. But it’s already there, in Seattle, New Rochelle and places yet undetected. The prime minister took to Twitter with the hashtag iorestoacasa: “I stay at home.” While hunkering down in your kitchen or bedroom makes epidemiological sense, it’s terrible for bars, boutiques and pizzerias. On Tuesday evening, as the streetlights flickered on, a flour-dusted pizzaiolo exited a restaurant near Piazza Navona while his boss taped signs on the window declaring the place shuttered. “‘Stay at home,’ they said!” the pizza maker railed. “Well, now we’re going to stay at home. We’re closed.” Similar scenes are playing out from Italy’s boot-top to toe. Northern hospitals are approaching the limits of their ability to care for those whose lungs are being ravaged by the disease. The Rialto Bridge in Venice, normally teeming with selfie-stick-wielding tourists, is empty. Dolomiti Superski, Europe’s biggest ski resort, has shut its lifts for the season despite pistes buried under more than five feet of snow. In Naples, trucks that look like something out of “Blade Runner” trundle through the Piazza del Plebiscito dousing the cobblestones in disinfectant.The unfolding financial crisis is deeply entwined with what’s happening in shoe stores, gelato shops, and hospital wards. Unlike the last financial contagion, which largely came from within the banking system, this is a shock to the entire economic corpus. As business grinds to a halt, the country risks a domino effect of unpaid bills and loans that threaten to ripple across the globe.“Basically, it’s a natural-disaster case,” Philipp Hildebrand, vice chairman at money manager BlackRock Inc., told Bloomberg TV. “If they don’t have customers for a couple of weeks, it becomes very hard to service their debt, it becomes hard to pay the rent.”Italy on Wednesday announced measures worth as much as 25 billion euros ($28 billion) to cushion the blow of the pandemic. Those include help for companies whose turnover has plunged, a moratorium on some mortgage payments, and support for workers facing temporary layoffs and parents who must stay home to take care of kids when schools are closed.On Thursday, European Central Bank President Christine Lagarde unveiled her own stimulus package, but held off on cutting interest rates. When Lagarde said, “We are not here to close spreads,” the Italian bond market plunged and yields shot up by the most ever. By the end of the day, U.S. stocks had registered their worst sell-off since 1987's Black Monday.Hildebrand’s comparison to a natural disaster is apt. This isn’t like a sovereign-debt crisis, a credit crunch, or even the invasion of Iraq. The only thing that comes close is the apprehension before a hurricane. As anyone who’s spent much time in Florida can attest, you know it’s coming, but you don’t know exactly when or where it will hit or how bad it will be. So you lay in supplies and make sure your Netflix subscription is paid up, and when it hits you don’t go outside because you might get killed by flying debris. That’s what Italy feels like. In a televised address Wednesday evening, Conte tightened things even further, ordering virtually all retailers other than grocery stores, pharmacies and gas stations to close until March 25. Factories can operate and public transportation, banks and the postal service will continue, but restaurants, cafes and bars are shut. With each passing day, Italy has become increasingly isolated from the outside world. Neighbors have clamped down at border crossings that for the past two decades have allowed unfettered passage under European Union rules. Austria and Slovenia are restricting entry to those who have tested negative for the virus, and Switzerland has sealed off nine minor crossings. On Thursday, Italians awoke to the news of Trump’s ban on most travel from Europe.No matter what form the landfall takes—from financial to epidemiological—the Italian experience has made one thing clear: When those shocks happen, it will seem like they arrived overnight.As recently as last Friday, the tourists had largely cleared out of Rome, but for locals life went on, with gusto. Restaurants were so packed that waiters could barely squeeze past the diners. Shoppers jostled for warm pizza bianca in bakeries. A butcher on Campo de’Fiori was so crowded customers needed to take a number. Then in the wee hours from Saturday to Sunday Conte announced the northern restrictions, and on Monday Italy became the first democratic country since World War II to impose a nationwide lockdown. Two weeks ago it had seemed like a big deal when cases topped 1,000. Now that number seems quaint.The outbreak that started in China in January has infected more than 130,000 people in at least 114 countries and territories, shuttering cities, disrupting trade and supply chains, and shaking financial markets. With Europe facing the prospect of a recession, Italy is at the center of it all. The country’s public debt stands at about 2.4 trillion euros, almost 135% of gross domestic product.Banks in other EU countries hold almost 450 billion euros in Italian sovereign debt. If the country goes under and those Italian holdings collapse in value, it would shake the foundations of the EU banking system. European banks are worried the crisis could even turn into a global meltdown like 2008. Their concern is that a virus-induced shutdown could spark a wave of defaults among the small and medium-sized enterprises that make up the economic backbone of countries such as Italy and Germany. That would wipe out profits at the lenders and potentially eat up much of the capital that regulators require them to set aside for a rainy day.The beleaguered Italian economy was already vulnerable to the economic impact of the virus, “a bit like an immuno-compromised patient,” says Rosamaria Bitetti, an economist at LUISS university in Rome. And like that patient, a sneezing, sniffling Italy puts the rest of the world at risk. “The impact could be systemic for all of Europe and beyond,” Bitetti says.It’s a peril that starts with people like Rossella Rocco. After eight years studying and working in Rome, in December the 29-year-old hairdresser moved back home to Corigliano-Rossano, a town of 77,000 in the southern region of Calabria. With state funding offered to young entrepreneurs launching businesses in the south, she leased a shop on the central piazza that she outfitted with a pair of hair-washing sinks and three salon chairs. But now, just a month before her planned opening, the pandemic has hit, with the town getting its first cases in the past few days. Even if customers show up, under the latest decree she’ll be barred from letting them in. She compares the experience to awaiting a tidal wave. “We’re bracing for impact: If people don’t leave the house there’s no business,” Rocco says. “I’m trying to stay positive, but this is devastating. Businesses like mine can’t survive without people.”Italy offers key lessons for the rest of the world: Impose harsh rules, fast, and make sure your message is clear. For weeks, Conte resisted demands from his government and opposition leaders for strict containment measures. Then he abruptly made his dramatic leap from locking down the north to shutting the entire country. And media leaks of the first decision, to seal off the north, sparked confusion—even panic—prompting thousands to rush onto trains to escape, and leading southern regions to order quarantines for arrivals from the worst-hit areas. Some economists say Italy’s early outbreak could prove that taking a short-term hit to business is worth the cost to stem the human and financial carnage. “Italy is a precursor of what will happen in the U.S. and in Europe because of the speed at which the virus spread,” says Nathalie Tocci, director of the International Affairs Institute in Rome. “Germany is on the same trend as Italy, but two weeks behind.”In another preview of what the U.S. might face, the extensive powers wielded by Italian regions—including health policy—led to delays in responding to the outbreak and arguments over limits on travel. Most Europeans bristle at restrictions on the scale of those imposed in China. “Italy’s weakness is the price to pay for an open society in a liberal democracy,” says Giovanni Orsina, head of the school of government at LUISS.Beyond the financial risks, there are those that can be truly terrifying to anyone anywhere: violence and disease. The turmoil in Trastevere wasn’t unique. Prisoners in at least two dozen facilities across the country rioted, leaving 12 inmates dead, apparently from drug overdoses after raiding the jail pharmacies.Yet so far, Italian officials insist there’s little risk of civil unrest or of the government falling because of the emergency. Of course, any prediction is hard to make given that infections haven’t yet peaked. Just a week ago, skiers were still booking Italian vacations and American university students were jetting around Europe. The nightmare scenario is health facilities collapsing in northern Italy, where hospitals are expecting shortages of intensive-care beds, ventilation machines and respirators. A rapid spread of the virus through the poorer south could expose the weak link in the national health system: A health ministry study says care in some southern regions is sub-standard.This is where a now-famous graph called “flattening the curve” comes in. The chart circulating on social media, which illustrates the thinking behind Italy’s extraordinary measures, shows two scenarios for any country, region or city. In one, cases spike all at once. In the second—represented by a flatter curve on a graph—the same number of infections spreads out over time due to “social distancing” such as school closures. A horizontal line represents the number of cases the local healthcare system can handle at any given time. The flatter curve stays below the line, but the spike scenario goes above it—meaning there aren’t enough beds or respirators for patients who need them. That’s what Italy is trying to avoid.For now, the hotspots in the north appear to be holding just below the line, in part by bringing in new equipment and, in recent days, moving intensive-care patients with non-corona ailments to hospitals farther away. But Italians are bracing for difficult decisions: On March 6, the national society of anesthesiology and intensive care published recommendations for dealing with “exceptional conditions of imbalance between needs and available resources” in admissions. The considerations for potential triage include a patient’s age and chance of survival. It’s no wonder that some Italians, especially older ones, are gripped with fear. On a recent morning at a Rome supermarket, a woman who appeared to be in her 70s blew up—more in terror than anger—at a man of a similar age standing close behind her, in violation of a new rule requiring at least a meter between people in public spaces. Taxi drivers wearing both masks and scarves around their faces are balancing the risk of infection with making their car payments.That fear has led to a sudden boom in grocery delivery services. The day after Conte announced the national lockdown, Rome supermarket entrances were jammed with bicycle couriers, mostly immigrants from Africa and South America, jostling for orders. By then Milan had settled into a home-delivery routine that has left residents waiting more than a week for a slot to get groceries.For Italians, it’s just another sign that the entrenched rhythms of daily life had to give way—from cappuccino at the bar in the morning, to an aperitivo in the piazza after work, to a pizza out with friends at night. The sacrifice isn’t fun, and borders on tragic: Weddings and funerals are banned, birthday parties postponed, educations derailed, businesses pushed to failure. But our friendly advice is when this virus gets to you, the sooner you accept the need to go into lockdown, the better.(Adds details on US market fall in 11th paragraph and updated infection numbers in 18th paragraph. An earlier version corrected the characterization of the Italian bond market move.)\–With assistance from Nicholas Comfort, Daniele Lepido, Sonia Sirletti, Giovanni Salzano and Antonio Vanuzzo.To contact the authors of this story: Vernon Silver in Rome at firstname.lastname@example.orgAlessandra Migliaccio in Rome at email@example.comJohn Follain in Rome at firstname.lastname@example.orgTo contact the editor responsible for this story: David Rocks at email@example.com, Melinda GrenierFor more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.