Italy and Iran have started to introduce the type of containment measures previously seen only in China, which has blocked tens of millions of people in the province of Hubei, the epicenter of the epidemic.
Italy reported a third death as cases increased and the country’s Venice carnival closed early.
The death toll confirmed by Iran has risen to eight, causing travel bans from neighboring countries.
So far, the virus has killed more than 2,400 people, with around 80,000 infected globally, although China remains by far the worst.
President Xi Jinping said that the epidemic has been the “biggest public health emergency” since the founding of the People’s Republic in 1949.
“This is a crisis for us and is a great test,” he said during state television comments.
In a rare admission, at a meeting to coordinate the fight against the virus, Xi added that China must learn from the “obvious deficiencies found” during its response.
The World Health Organization (WHO) has praised Beijing for its management of the epidemic, but China has been criticized at home for silencing the first warnings of an informant doctor who later died of the virus.
South Korea said it raised its alert level to the highest level after the number of infections nearly tripled to 602 over the weekend.
The country now has the highest number of infections outside of China, apart from the Diamond Princess cruise ship docked in Japan.
South Korea reported three deaths on Sunday, bringing the death toll across the country to five. The Yonhap news agency later reported a sixth death.
About half of South Korean cases have been linked to the Shincheonji Church of Jesus sect in the southern city of Daegu, where thousands of members have been quarantined or asked to remain at home.
Cases in Italy rose to 152 on Sunday, including three deaths.
The panic of the virus crept onto the catwalks, leading to the cancellation of some fashion shows at Milan Fashion Week. Others were kept behind closed doors and streamed.
Most cases are confined to the northern city of Codogno, approximately 70 kilometers (43 miles) south-east of Milan.
More than 50,000 people in about a dozen cities in northern Italy have been told to stay home and police have set up checkpoints to impose a blockade.
Neighboring Slovenia has asked vacationers returning from ski resorts in northern Italy to be especially vigilant for symptoms.
Italy became the first European country to report that one of its citizens died on Friday from the virus.
Two other victims occurred over the weekend, but Prime Minister Giuseppe Conte urged people to “not panic” and asked them to follow the advice of the health authorities.
“The rapid increase in cases reported in Italy in the past two days is worrying,” said World Health Organization spokesman Tarik Jasarevic.
Jasarevic added that not all reported cases have clear epidemiological links, such as travel history in China or contact with a confirmed case.
“At this stage, we need to focus on limiting further human-to-human transmissions.”
Iran has ordered schools, universities and cultural centers to close in 14 provinces after eight deaths – most outside East Asia.
The outbreak in the Islamic Republic emerged Wednesday and quickly rose to 43 confirmed infections, a sudden increase that caused restrictions on regional travel.
Armenian Prime Minister Nikol Pachinian said his country will close the Iranian border and suspend flights.
Like the Italian leader, he also said there is no reason to panic.
But Paul Hunter, a professor of medicine at the British University of East Anglia, said that the situation in Iran has “important implications” for the Middle East.
“Iran is unlikely to have the resources and facilities to adequately identify cases and manage them adequately if the number of cases is high,” said Hunter.
Pakistan and Turkey have announced the closure of the land crossings with Iran, while Afghanistan has declared to suspend the journey to the country.
The outbreak in China remains concentrated in the city of Wuhan – closed a month ago – where the virus is believed to have emerged from a live animal market in December.
China’s infection rate has slowed, but the flip-flop on counting methods has wreaked havoc on its data.
There was also growing concern about the difficulty of detecting the virus.
Japan confirmed on Sunday that a woman who tested negative and disembarked from the Diamond Princess cruise ship affected by the virus subsequently tested positive.
Similarly in Israel, authorities confirmed that a second Israeli citizen returned from the ship had proved positive. They were among the 11 Israelis who had been allowed to get off the ship and return home after initially having tested negative.
Japan has been criticized for handling cases aboard the quarantined ship off Yokohama.
A third passenger died on Sunday, the Japanese health ministry said, without specifying whether it was the result of the virus.
Four Britons who returned from Diamond Princess on Saturday also tested positive for COVID-19 disease, the NHS health service said. (AFP)