SEOUL, South Korea (AP) -- The head of the World Health Organization on Thursday praised beleaguered South Korean officials and exhausted health workers, saying their efforts to contain a deadly MERS virus outbreak have put the country on good footing and lowered the public risk.
Margaret Chan said it's a good sign the disease has so far been confined to a handful of hospitals and isn't spreading in the wider community.
"All the new information is reassuring, but that reassurance must be qualified," Chan said at a news conference in Seoul. She cautioned that much about MERS is unknown and there's still a need to strengthen monitoring and quarantine efforts.
Despite the optimism, there is still widespread worry here, and the discovery of new cases among people who managed to slip through quarantine measures has raised questions about officials' ability to control the outbreak.
Middle East respiratory syndrome has killed 23 people in South Korea, the biggest outbreak outside the region where it was first seen in 2012. More than 6,700 people are isolated at home and in medical facilities, and more than 160 have been diagnosed with MERS nearly a month after the outbreak started with a 68-year-old man who had traveled to the Middle East, according to Seoul's Health Ministry.
Most of the fatalities have been people with existing medical conditions, such as respiratory problems or cancer.
Chan said South Korea's initial sluggish reaction might have contributed to the wider-than-expected spread of a virus that usually moves poorly between people. South Korean officials early on struggled to trace and identify the contacts of those infected, and their initial refusal to name the hospitals where MERS patients had been treated was blamed for fanning public fear and unwillingness to cooperate.
"After a slow start, the government put in place one of the strongest responses I've seen," Chan said.
Officials say the outbreak has already peaked and could be defused by the end of the month. Experts say the coming week could test the government as the number of people isolated at home and in medical facilities approaches 7,000.
Critics, including Seoul Mayor Park Won-soon, say government officials accelerated the spread of MERS by failing to enforce tight control measures at Seoul's Samsung Medical Center, which was belatedly shut down over the weekend because it continued to be the main source of infections.
Dozens of patients, medical staff and visitors have been infected with MERS at the hospital, one of the country's biggest, and are believed to have contacted thousands of other people before their conditions were confirmed.
The sheer size of the exposure at the hospital suggests the country could see another large wave of infections, according to Jacob Lee from the infectious disease department at Seoul's Kangnam Sacred Heart Hospital.
Lee said infected medical staff at Samsung could be the next major spreaders of the virus. The country's recent MERS cases include a Samsung doctor, nurse, X-ray technician and an ambulance worker.
Government officials said they are monitoring the health of some 3,000 people who had various levels of contact with the Samsung ambulance worker, who transported dozens of patients to the hospital and used the subway to commute before his condition was confirmed. Officials are also calling and texting some 50,000 people who visited the hospital in late May and early June to ask if they are experiencing MERS-related symptoms such as fever, cough and shortness of breath.
There is no vaccine to prevent the disease.
WHO said in a statement Wednesday that the spread of MERS in South Korea doesn't merit being declared a global emergency.