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People wait to be tested for COVID-19 outside of a temporary screening station in Seoul’s Dongdaemun District on Monday morning. (Yonhap News)

South Korean health authorities have predicted that the Omicron variant of the COVID-19 virus could become the dominant variant in the country within one to two months. The transmission rate has been twice as fast as the Delta mutation, which is currently the dominant variant in Korea.

Lee Sang-won, head of epidemiological investigation and analysis at the Central Disease Control Headquarters (CDCH) said at a press briefing on Monday afternoon that “the speed at which Omicron is spreading is very fast.” He added that “there is a possibility that it will become the dominant variant within the next one to two months.”

Lee also added the average incubation period of Omicron was 3.6 days and the average generation interval was 3.1 days, which was shorter than the average incubation period of the Delta variant of three to five days with an average generation period of 2.9-6.3 days.

The generation period refers to the interval between the occurrences of symptoms in an infector-infectee pair. In addition, health authorities conducted an epidemiological investigation focusing on the cases of the church in Incheon and a daycare center in southeastern Korea, where the Omicron virus was first confirmed in Korea. The results found that Omicron had a secondary attack rate of 44.7% — more than twice as high as Delta’s, which is about 20%.

In South Korea, 19.8% of patients confirmed to have contracted the Omicron variant were asymptomatic at the time of diagnosis, and all are currently exhibiting mild symptoms. Initial symptoms reported included fever, sore throat, and cough. However, authorities explained that 92.7% of confirmed cases of the Omicron mutation occurred among those under the age of 60, so additional analysis is needed to determine the severity of the variant.

According to Lee, five out of 178 people infected with Omicron in Korea had pneumonia. He noted that “it is dangerous to be optimistic about the Omicron variant due to the mild symptoms” adding that “further, more accurate severity assessment is necessary.”

One more person was confirmed to have contracted the Omicron variant in South Korea even after receiving the booster shot, raising the total number of breakthrough infections to five. The three patients who experienced breakthrough infections were confirmed to have received the vaccine made by Johnson & Johnson’s Janssen division. However, more than half of those who contracted the new variant — including 88 unvaccinated and 4 people who received a first vaccine dose — had not been fully vaccinated. As a result, authorities are stressing the need for a third vaccination to curb the spread of the new variant and prevent more serious outcomes.

Park Young-joon, head of the epidemiological investigation team at the CDCH, explained, "According to the recently reported UK data, the effectiveness of preventing infection differs depending on the type of vaccine used for the second shot, but when the third vaccine is administered, all of them report that the effectiveness of preventing infection rises to 80%."

Meanwhile, the CDCH announced that there were 5,318 new confirmed cases as of the end of the day Sunday. After hitting a record high of 7,850 cases on Wednesday, the numbers fell to the 6,000-7,000 range, then dropped beneath the 6,000-case mark. Moreover, in the past two days, the number of critical cases went down by 28 from 1,000 to 997 cases, with 54 deaths reported, bringing the total to 4,776.

Still, the number of confirmed cases per 100,000 was 16.8 among those in their 60s or older — 1.5 times higher than that of those aged 20 to 59. Of the cases requiring critical care, 85% were concentrated among older populations. The proportion of individuals aged 60 and over among the total number of confirmed cases is on the decline from 35.8% on Nov. 28 to 33.5% on Dec. 4. These figures have now further declined to 30.5%.

Son Young-rae, head of the social strategy division at the Central Disaster Management Headquarters, said, “The rate of third dose vaccination for those aged 60 and over has risen to 56.7%,” adding, “We believe that the spread of the third vaccination is leading to a decrease in the proportion of older patients.”

Regarding the recent trend of elderly confirmed patients and patients with severe cases, Jung Jae-hun, a professor of preventive medicine at Gachon University College of Medicine, said, “We are carrying out booster vaccinations and emergency checks, so it will be possible to prevent the situation from deteriorating further than currently.” He noted the need to “buy time” for the reorganization of the medical system.

“In the current situation, booster vaccinations are just about the only option,” he said.

By Lim Jae-hee and Jang Hyeon-eun, staff reporters

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