The World Health Organization and the Ministry of Health and Welfare’s joint mission Saturday characterized the Middle East respiratory syndrome outbreak that began here last month as “large and complex” and recommended continued vigilance.

The joint mission said strengthening of contact tracing, monitoring and quarantine as well as expanded lab testing will prevent the further spread of the MERS coronavirus. There has been no mutation in the virus, the joint mission said, explaining that it shows a similar epidemiological pattern to previous hospital-related MERS outbreaks in the Middle East.

While the mission said that it found no evidence that MERS was circulating in the community, the confirmation of two cases of quaternary infection since Saturday have raised concerns that MERS is on the brink of spreading to the community. A private ambulance driver who transported a MERS patient and an accompanying person have been diagnosed with the disease, making them the first-ever quaternary infection patients in the world.

Adding a sense of crisis to the situation is the partial shutdown of Samsung Medical Center, where a third wave of infections is expected following the second that was caused by a MERS patient who stayed at the emergency room for two days. An aide at the hospital who assists patients on wheelchairs was found to have worked for nine days with MERS symptoms before being diagnosed. It is estimated that he had directly assisted 76 patients, raising the possibility of another outbreak of infections at the hospital.

Lee Jong-koo, head of the Seoul National University Center for Global Medicine, describing MERS as a form of cold, cautioned against overreaction, saying that the situation cannot be seen as a national emergency.

Indeed the death rate, estimated at 40 percent, has remained at slightly above 10 percent in Korea. Even then, most of the MERS death cases have been elderly patients with preexisting conditions. The number of MERS patients stood at 145 as of Sunday morning, with 14 deaths and 10 making complete recovery.

The WHO-Health Ministry joint mission recommended prevention of travel, especially overseas, of infected persons and people who came into contact with infected persons. A Korean man who has traveled to Slovakia on business has been hospitalized there with MERS-like symptoms and awaits test results. Earlier, a man who had been in close contact with a MERS-confirmed patient traveled to China despite medical advice, and was diagnosed with the MERS coronavirus there where he remains hospitalized.

A woman suspected of having MERS was forcibly taken from her home by police to a hospital when the health authorities were unable to persuade her to check into a hospital to be quarantined. It must be difficult for the more than 4,000 people who are under quarantine, who must remain in isolation for a maximum of 14 days. However, quarantine appears to be the most effective way to contain the spread of MERS and the public should exercise good citizenship and comply.

The government, meanwhile, should keep the public informed of ongoing developments. The health authorities’ blocking of information in the early days of MERS contributed significantly to its quick spread in hospitals. The WHO said that continued monitoring for community infections is critical, meaning that the authorities should not completely rule out the possibility of community infections. In such a scenario, information sharing will be vital in containing the spread of the virus as well as unnecessary panic.