Infections in South Korea surpass 500, and a fourth death is reported.
South Korea, where a coronavirus outbreak has mushroomed into the hundreds in just days, reported 123 new infections and a fourth death on Sunday, as the government sternly warned its people to cooperate with quarantine efforts.
The country now has 556 confirmed cases. More than half of those people are either members of the Shincheonji Church of Jesus, a secretive religious sect, or their relatives or other contacts. Many cases are in the southeastern city of Daegu, which has essentially been placed under a state of emergency.
Prime Minister Chung Sye-kyun on Saturday called the situation “grave” and urged citizens to cooperate with the government and avoid large political rallies, which have continued in the capital, Seoul, despite a city ban.
“The government will sternly deal with acts that interfere with quarantine efforts, illegal hoarding of medical goods and acts that spark uneasiness through massive rallies,” Mr. Chung warned in a nationally televised address.
The spike of cases in South Korea and a rising death toll in Iran added to fears that the window to avert a global pandemic was narrowing. The World Health Organization warned African leaders of the urgent need to prepare for the virus; it identified 13 African countries as priorities because of their direct links to China, which still accounts for the vast majority of confirmed infections and deaths.
On Sunday, China raised its official numbers to 76,936 cases and 2,442 deaths.
The State Department raises its travel advisories for Japan and South Korea.
The State Department raised its travel advisories for Japan and South Korea on Saturday to Level 2, the second-lowest out of four grades, recommending that travelers “exercise increased caution” due to the coronavirus outbreak.
The advisories said that while many Covid-19 cases have been associated with travel to and from mainland China, or contact with someone who had recently been there, South Korea and Japan were now reporting “sustained community spread.” That means it is not known how or where people became infected, and the spread is ongoing, the advisories said.
In Japan, health officials are investigating clusters of cases that have taken on more urgency now that hundreds of passengers have been released from the Diamond Princess cruise ship, which had the largest concentration of the coronavirus outside mainland China. Cases in South Korea surged to 556 on Sunday, with four deaths.
Japanese officials said Saturday that 23 of the Diamond Princess passengers had mistakenly been cleared without a recent valid test. Those passengers have since been tested and posed “no risk of infection,” the Japanese Health Ministry said.
A vast containment effort relies on local officials.
Since early February, thousands of people returning to the United States from mainland China have been asked to isolate themselves at home for 14 days. Preventing the spread of infectious disease is the essence of public health work, but the scale of efforts by state and local health departments across the country to contain any potential spread of the coronavirus has rarely been seen, experts said.
Local health officials check in daily by email, phone or text. They arrange tests for people who come down with symptoms, along with groceries and isolated housing, in some cases. There is no centralized tally in the United States of people being monitored or asked to remain in isolation, and they are scattered across the nation’s nearly 3,000 local health jurisdictions.
People arriving from mainland China are added each day, while those who have completed 14-day “self-quarantine” periods are released from oversight. In California alone, the department of public health has been monitoring more than 6,700 returning travelers from China. Health officials in Washington State have tracked about 800, and officials in Illinois more than 200.
Even as the first of 34 confirmed coronavirus patients in the United States have recovered in recent days, health officials say they are preparing for what some fear could still be a much wider outbreak.
So far, officials say, the containment effort has been largely orderly. The only known transmission of the virus in the United States has involved people in the same household. But no matter how effective health workers are in monitoring their charges, “there will always be some leakage,’’ said John Wiesman, the secretary of health in Washington State.
“There is no way, with something this large, that you can make it seal-proof,’’ Dr. Wiesman said. While enforcing total compliance with isolation orders may not be possible, he said, “We have to try for 80 to 85 percent, and hopefully that will work.’’
Russian disinformation blames the U.S. for the virus.
State Department officials say that thousands of Russia-linked social media accounts are spreading disinformation about the coronavirus, including a conspiracy theory that the United States is behind the Covid-19 outbreak.
American monitors identified the campaign in mid-January. Agence-France Presse first reported on the assessment on Saturday.
“Russia’s intent is to sow discord and undermine U.S. institutions and alliances from within, including through covert and coercive malign influence campaigns,” said Philip Reeker, the acting assistant secretary of state for Europe and Eurasia.
“By spreading disinformation about coronavirus, Russian malign actors are once again choosing to threaten public safety by distracting from the global health response.”
The effort was described as being carried out by several thousand Russia-linked accounts on Instagram, Facebook and Twitter, which post similar messages at similar times in English, Spanish, French, German and Italian.
Fringe theories of uncertain origin have accused China of engineering the virus, including suggestions that it is an escaped bioweapon.
Misinformation about the virus — whether shared purposefully or unwittingly — is so rife that the World Health Organization has called it an “infodemic.” The W.H.O. has been working with big tech companies to try to quell the flood of rumors and falsehoods.
Reporting was contributed by Choe Sang-Hun, Derrick Bryson Taylor, Austin Ramzy, Amy Harmon, Farah Stockman and Edward Wong.