Sweeping travel bans are accelerating around the globe as governments increasingly isolate people at home and within their borders to slow the unfolding coronavirus pandemic.
In the US, stocks dropped so fast that trading halted for the second time this week.
President Donald Trump, who had downplayed the virus for weeks, delivered a sombre Oval Office address announcing strict rules on travel from much of Europe after accusing governments there of failing to respond quickly to the threat.
The State Department followed with an extraordinary warning to Americans to “reconsider travel abroad” as well.
The European Union quickly condemned Mr Trump’s “unilateral” decision, declaring the virus a “global crisis, not limited to any continent and it requires co-operation rather than unilateral action”.
The virus detected three months ago in China has produced crippling outbreaks in Asia, Europe and the Middle East, ignited global financial panic and in the last week has seen dizzying developments that are erupting by the hour.
Those include an official designation of “pandemic” from the World Health Organisation, a dramatic halt to much travel between the US and 26 European countries, and infections being announced in rapid-fire pace by Hollywood celebrities, sports stars and political leaders as well as ordinary people on cruise ships.
In Italy’s Lombardy region, the virus hospitals were overwhelmed with both the sick and the dead.
Around the world, nursing homes emptied of visitors to protect the elderly, who are especially vulnerable to the virus.
More than 127,000 people in more than 110 countries have been infected.
The vast majority are in just four countries: China and South Korea – where new cases are declining – and Iran and Italy, where they are not.
The spread has slowed so much in China that the government offered to send a medical crew to Italy and surplus supplies to Iran and other countries in need.
More than 4,700 people have died worldwide.
In Italy, new restrictions closed restaurants, cafes and retail shops on Thursday after the prime minister imposed a nationwide lockdown on personal movement earlier in the week.
Grocery stores, pharmacies and outdoor markets were allowed to operate, as were newspaper stands.
Rosanna Farina, whose family has run a newspaper kiosk in Rome’s historic centre since the 19th century, was torn on whether it was worth staying open.
“So few people are out and about. People are terrorised,” she said, wearing a scarf around her face.
“I’d rather be home. I’m worried, even if I’m keeping a distance.”
Ireland, Denmark, Norway, Lithuania, Algeria and Slovakia joined the growing list of countries shutting down their school systems, and Europe’s most successful football team, Real Madrid, put all its players into quarantine after one tested positive.
Even remote Mount Everest closed for business.
Chinese mountaineering officials cancelled spring climbs from their side of the mountain, while on the other side in Nepal, operators said cancellations were pouring in.
Europeans were adjusting to the American travel restrictions, which hit some of the world’s most heavily travelled routes and threw travel plans into chaos.
“We were going to get married in Las Vegas, with Elvis. It was going to be epic,” said Sandrine Reynaert, a Parisian who had to cancel the April 20 ceremony.
Her future husband already has the date engraved in his ring.
Britain and Ireland were exempt, despite imposing far fewer restrictions in response to the virus than many EU countries, raising questions about the coherence of the US policy.
Mr Trump accused Europe of not acting quickly enough to address the “foreign virus” and claimed that US clusters were “seeded” by European travellers.
Across the US, cases now number more than 1,300.
As the pandemic grips Europe and the US, it continues to ebb in China, where the first cases of Covid-19 emerged in December.
It reported a record low of just 15 new cases on Thursday.
So far, more than three-quarters of China’s patients have recovered.
Most people infected by the new virus have only mild or moderate symptoms, such as a fever and cough, though symptoms can be severe, including pneumonia, especially in older adults and people with existing health problems.
Recovery for mild cases takes about two weeks, while more severe illness may take three to six weeks, according to the WHO.