'Stealth Omicron' Overseas Inflow Share Soars from 3.2% to 17.4% (Update)

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[Asia Economy Reporter Na Ye-eun] The proportion of the BA.2 lineage, known as the 'Stealth Omicron,' among imported Omicron cases has significantly increased.

On the 16th, the Central Disease Control Headquarters (CDCH) stated in a briefing that "as Omicron spreads globally, its detailed lineages are also changing," based on data on the detailed lineages of Omicron variant viruses both domestically and internationally.

The Omicron variant is broadly classified into four detailed lineages: BA.1, BA.1.1, BA.2, and BA.3. Among these, BA.2 is called the 'Stealth Omicron' because its mutation types are difficult to distinguish.

Current Share Status of Domestic Variant Virus Lineages. / Photo by Central Disease Control Headquarters, Yonhap News Agency

According to the CDCH, as of January, 53.2% of domestic Omicron infections were caused by the BA.1.1 lineage, followed by BA.1 (7.1%) and BA.2 (1.4%).

Among imported infections, BA.1.1 was also the most common at 42.5%, followed by BA.1 (38.8%) and BA.2 (17.4%). Notably, the proportion of Stealth Omicron (BA.2) imports increased sharply from 3.2% in December last year to 17.4% in January.

The CDCH stated, "The vaccine effectiveness between BA.1 and BA.2 is analyzed to be similar, so the characteristic differences between detailed lineages are likely not significant," adding, "Some countries suggest that BA.2 may have higher transmissibility than BA.1, so further research is needed on the transmissibility, severity, and vaccine and treatment effectiveness of BA.2, which currently has a relatively low share."

This content was produced with the assistance of AI translation services.