Updated at 12:23 p.m. ET, Feb. 25
The number of new coronavirus cases in South Korea had a major spike over the weekend.
By Sunday, Korea Centers for Disease Control and Prevention reported that the total number of confirmed cases in the country rose to 556.
As of Tuesday, the number of confirmed cases was just 31.
Many of the new patients were located in or near Daegu, South Korea's fourth-largest city, where dozens of people linked with a Christian sect known as the Shincheonji Church of Jesus have shown symptoms of respiratory illness. The church, which has about 150,000 adherents, says it has shared with authorities the names of members who may have been exposed to the virus, and it is encouraging them to enter quarantine.
Meanwhile, in the nearby city of Gumi, Samsung said it is shutting down a mobile device factory after confirming a case of the coronavirus at the facility. The Korean electronics giant said it is shuttering the factory at least through the weekend.
"The company has placed colleagues who came in contact with the infected employee in self-quarantine and taken steps to have them tested for possible infection," the company said in a statement released Saturday.
At least four patients in South Korea have died from the disease now known as COVID-19, while at least 18 have recovered and been released from care. Thousands more are still undergoing testing for the respiratory disease.
A few of the cases include South Korean nationals who recently traveled to Israel and the West Bank, NPR's Daniel Estrin reports. Officials in those areas have asked anyone who came in contact with the tourists to quarantine themselves for two weeks.
Also, Israel is refusing entry to foreign visitors who have been in Thailand, Singapore, China, Hong Kong and Macau in the last 14 days.
All told, there have been nearly 79,000 confirmed cases of the coronavirus worldwide, more than 2,400 of which have ended in a patient's death. The vast majority of those cases so far have been reported in mainland China, where the outbreak has its roots in the city of Wuhan — though the number of new confirmed cases there reportedly has been declining recently.
But the virus has not stopped at the Chinese border, Japan has seen recent leaps in cases of its own. And health officials are anxiously watching the numbers swell in countries even farther afield.
In Europe, the virus has spread in Italy, which now reports 229 cases and 6 fatalities. Austria, Croatia and Switzerland have also reported their first cases.
"The increasing signs of transmission outside China show that the window of opportunity we have for containing this virus is narrowing," Tedros Adhanom Ghebreyesus, the director-general of the World Health Organization, told a news conference Saturday.
Of particular concern, he said, are "the number of cases with no clear epidemiological link, such as travel history to China or contact with a confirmed case." He described as especially worrisome the disease's spread in Iran, where there are 61 cases as of Tuesday and 12 fatalities.
He said that WHO has sent testing kits to Iran. And though just one confirmed case has been reported in Africa — in Egypt, specifically — Tedros warned that because of the robust trading relationship between China and some countries on the continent, health officials should be preparing for its arrival before long.
"Our biggest concern continues to be the potential for COVID-19 to spread in countries with weak health systems," he said.
"We know a little bit more about this virus and the disease it causes. We know that more than 80% of patients have mild disease and will recover, but the other 20% of patients have severe or critical disease, ranging from shortness of breath to septic shock and multi-organ failure," said Tedros.
"These patients require intensive care, using equipment such as respiratory support machines that are, as you know, in short supply in many African countries."