New Omicron subvariant BA.2.12 begins to show in South Korea

Picnickers crowd the riverside park in Seoul’s southwestern Banpo on Sunday. South Korea ended all social distancing restrictions on April 18. (Yonhap via The Korea Herald/Asia News Network)

SEOUL — The Korea Disease Control and Prevention Agency said Tuesday Omicron’s more transmissible new subvariant, BA.2.12, made up 10 percent of the circulating variants in the country.

The agency’s weekly analysis announced Tuesday showed omicron’s BA.2 lineage, which was first spotted in late January, showed up in 94.2 percent of cases in the third week of April. In a further breakdown of variants, BA.2.3 made up 63.5 percent of cases; BA.2, 16.8 percent; BA.2.12, 10.3 percent; BA.2.5, 1 percent; and BA.2.10, 2.4 percent.

To date no cases of BA.2.12.1, one of two BA.2 subvariants now spreading in northeastern US, have been discovered in the country, the agency said. The other is BA.2.12. The agency said the two new subvariants — BA.2.12 and BA.2.12.1 — are estimated to be about 20 percent more transmissible than BA.2 that has been dominant since the last week of March.

According to the agency, recently, about 1,600 to 2,000 cases have been whole-genome sequenced per week. As of April 20, a total of 13,138 counts of whole-genome sequencing have been conducted this year.

“After the exponential omicron surge, health agencies including the US CDC are saying sequencing rates are no longer meaningful,” said the head of the agency’s surveillance analytics team, Kim Eun-jin. She claimed that Korea was “sequencing far more” than the globally recommended standard.

She added that about 50 percent of “imported” cases, or cases found among international passengers, are being sequenced. So far in April 766 cases were confirmed in arriving passengers.

The agency said from the start of the pandemic through April 16 this year, there have been 55,906 cases of suspected reinfection, of which 55,841 were second infections and 65 of them for the third time. Among them 72 developed severe symptoms and 52 died.

The agency defines suspected reinfection as a positive test after 90 days have elapsed since the primary infection, regardless of symptoms. A positive test following symptoms or exposure at least 45 days from the first infection also counts as a suspected reinfection.

Lee Sang-won, leading the agency’s epidemiologic analysis team, said Korea has been seeing about a 30 percent weekly decline in new cases over April and that this trend was anticipated to continue for about a month or two.

In the last two weeks the country counted an average of 107,515 cases and 183 deaths each day, down from 244,423 cases and 321 deaths seen daily in the previous two-week period from March 29-April 11.

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