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Workers sanitize a KTX train in Goyang, Gyeonggi Province, on Feb. 6. (Kang Chang-gwang, staff photographer)

It takes less time for the novel coronavirus to spread from the first patient to a second, and from the second to a third, than for SARS (Severe Acute Respiratory Infection) or MERS (Middle East Respiratory Infection), suggesting that the coronavirus is more contagious. But mere infection doesn’t often lead to a severe case of the disease, experts say. In press conferences held by the Korean Society of Infectious Disease on Feb. 6 and by a central clinical task force for the novel coronavirus on Feb. 7, infectious disease experts said that the local transmission of the coronavirus in South Korea will probably be limited, but urged authorities to remain alert about cases in which the route of transmission cannot be traced.

Why has the novel coronavirus been spreading so rapidly when it’s reproduction number (that is, the average number of people to whom an infected person transmits the virus) is lower than MERS and SARS? The answer, analysts say, is that the coronavirus has a short generation time.

“The time it takes for one patient to infect a second patient, and for the second patient to infect a third, is known as the generation time. We think that the novel coronavirus is spreading so rapidly because its generation time tends to be very short,” said Bang Ji-hwan, head of the central clinical task force and director of the central contagious disease hospital at the National Medical Center.

But analysts say that the second round of infections hasn’t really taken off even in China and has only occurred on a very limited scale in South Korea. “If local transmission of the virus was occurring at a high level in South Korea, we ought to be seeing a large number of patients with unexplainable cases of pneumonia. But there’s only been a single case like that in Gyeongju [North Gyeongsang Province] recently,” said Shin Hyeong-sik, head of the infectious disease research center at the National Medical Center.

“The reason the number of patients hasn’t been increasing outside of China [as it has inside China] is because of the [particular] conditions in Wuhan that facilitated the transmission of the virus in the initial phase. As can be seen in the differences between the situation in Wuhan and in the rest of China, the propagation of the disease will depend on our response,” said Heo Jung-yeon, a professor of infectious diseases at Ajou University Hospital.

“We need to remain alert to the possibility of an increasing number of domestic cases that show little epidemiological correlation,” said Kim Nam-jung, a professor of infectious diseases at the Seoul National University College of Medicine.

The majority of coronavirus patients in South Korea are in a stable condition.

“The average age of domestic patients is 49 years since most of the infected are people capable of traveling [overseas]. But if this disease is unleashed in hospitals [where there are many patients vulnerable to infection], it would be hard to prevent the occurrence of fatalities,” Kim Nam-jung said.

But some experts think the coronavirus’s fatality rate will fall below its current level of 2%.

“There have been two deaths out of some 200 cases outside of China. The patient in Hong Kong had a heart attack, and the patient in the Philippines likely died of a secondary infection. Considering the possibility [that patients] have died of other causes, the fatality rate is extremely low,” said Shin Hyeong-sik.

Clinical experience indicates that the coronavirus is causing less lung damage than SARS and MERS.

“X-ray images taken of the patients show white areas of inflammation in the lungs [like regular cases of pneumonia], but the actual symptoms, such as shortness of breath, are less severe. This suggests that this type of pneumonia doesn’t cause as much inflammation,” Bang said, while cautioning that “this is a limited result based entirely on domestic cases of the disease.”

How is it treated?

“We have medication for the swine flu, but the only way to treat the novel coronavirus is by tackling its symptoms. Some people are using AIDS medication, but there’s still disagreement about whether that needs to be administered when cold-like symptoms first appear,” said Baek Gyeong-ran, a professor of infectious disease at Samsung Medical Center.

The reason that patients are nonetheless being cured is because their bodies’ immune systems are functioning. “A healthy adult can make a natural recovery as the operation of the immune system eliminates the virus sometime between 10 days and three weeks. It takes longer for antibodies to form because this is a new type of infectious disease,” Shin said.

By Park Hyun-jung and Park Da-hae, staff reporters

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