hankyoreh

in Seoul’s Gangnam district

On June 6, the Ministry of Health and Welfare announced the results of an analysis showing that the coronavirus causing the current outbreak of Middle East Respiratory Syndrome, or MERS, in South Korea has not mutated. These findings put to rest domestic speculation that the virus had mutated to allow airborne transmission, which would made it much more contagious.

So what could have enabled MERS to spread so rapidly, infecting 64 people in just 18 days?

“When we sequenced the MERS virus that came into South Korea, we found it to be virtually identical to the virus that has caused disease in Saudi Arabia and other parts of the Middle East. We did not detect any major changes or mutations,” said Lee Ju-shil, director of South Korea’s National Institute of Health, which is affiliated with the Centers for Disease Control at the Ministry of Health.

After collecting sputum from the second person in South Korea to be diagnosed with MERS (63, the wife of the first patient), the institute first isolated and cultured the virus and then analyzed its DNA sequence.

Next, the institute shared this information with the South Korean Society of Virology, the US Centers for Disease Control (CDC), and the Netherlands Institute for Health Sciences at the Erasmus Institute to compare the characteristics of the MERS virus that had entered South Korea with the virus in the Middle East.

“In our comparative analysis, we found that the DNA of the virus taken from the second patient diagnosed with MERS was 99.82% the same as the DNA of the virus that caused the epidemic in Saudi Arabia in 2013. This means that the MERS virus that is spreading in South Korea is not some new mutation but is rather the same as the MERS virus that is currently active in the Middle East,” Lee said.

The analyzed DNA was extracted from the virus taken from the second patient, whose symptoms were so mild that she was supposed to be released from the hospital on Sunday. When asked whether this virus might be different from the viruses in the first, 14th, and 16th patients, who have been much more contagious, the ministry said, “We believe that the virus itself derived from the same source. Even in Saudi Arabia, where more than a thousand people have been infected, no mutations have been discovered.”

Since the announcement that the virus had not mutated, there have been a number of theories that propose to explain how MERS could have spread so rapidly. First of all, the viability of viruses decreases greatly in conditions of high temperature and humidity. It is possible that South Korea’s climate during May and June just happens to be the climate in which the virus thrives.

Another theory for why the first, 14th, and 16th patients caused so many secondary and tertiary infections is that these patients were hospitalized from five to seven days after they began to experience the symptoms of MERS, which happens to coincide with the period when the virus is most active.

Even though the first patient was hospitalized at Samsung Medical Center between May 18 and 20, none of the 400 people or so who came into contact with him were infected. According to this theory, the virus had already lost much of its strength by this time.

In regard to why so many people - 37 altogether - were infected at St. Mary’s Hospital in Pyeongtaek, the Ministry of Health explained that the patient served a large number of patients suffering from chronic diseases, including the elderly, people with low immunity, and diabetes patients. Such people are vulnerable to viruses.

It is also possible that the unique hospital culture in South Korea enabled MERS to spread more quickly. South Korean hospitals have many shared rooms, family members take care of patients, and hospital visits are fairly relaxed.

By Lee Keun-young, senior staff writer

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