"New Variant Every 6 Months"... Stealth Omicron Raises Concerns of Spread to Other Variants

Stealth Omicron Detection Rate 56.3%, Becoming Dominant Strain
346 Suspected COVID-19 Reinfection Cases
Variants Like 'Deltacron' Confirmed Abroad
Monthly 30% Probability of New COVID Variants in Korea

On the 18th, when the COVID-19 variant outbreak entered its peak phase, medical staff at the temporary screening clinic in Seoul Plaza closely monitored the rapid antigen test kit results of a test subject. On that day, 407,017 new confirmed cases were reported, bringing the total to 8,657,609. There were also 301 deaths recorded in a single day. Photo by Kim Hyun-min kimhyun81@

[Asia Economy Reporters Ki Ha-young and Kim Young-won] Since the outbreak of COVID-19, new variants have emerged at an average interval of six months, raising calls to prepare for the post-Omicron variant era. The sublineage of Omicron, known as 'Stealth Omicron (BA.2),' has already become the dominant strain in South Korea, increasing concerns about reinfections caused by new variants.

According to the Central Disease Control Headquarters on the 29th, the Omicron sublineage 'BA.2' became the dominant strain domestically last week (March 20?26). The detection rate of BA.2 among confirmed cases in South Korea rose from 22.9% in the first week of this month to 26.3% in the second week, 41.4% in the third week, and surpassed 50% at 56.3% in the fourth week. The detection rate of BA.2 among imported cases last week surged to 71.1%.

'Stealth Omicron' Becomes Dominant...346 Suspected Reinfection Cases

BA.2 is known to be 1.3 to 1.5 times more transmissible than the original Omicron variant. However, clinical severity and hospitalization rates reportedly show no significant difference.

Countries overseas are also experiencing an increase in confirmed cases due to BA.2 becoming dominant. Germany, Austria, and others had already reached the Omicron peak in January and February but have recently seen the largest surge in cases over the past one to two weeks.

The emergence of new variants has heightened concerns about reinfections. Since COVID-19 was first introduced to South Korea in January 2020, there have been a total of 346 suspected reinfection cases as of the 27th. This equates to 2.88 reinfections per 100,000 infected individuals. Until June 2021, when the original COVID-19 was dominant, there were only two suspected reinfection cases. However, during the Delta-dominant period (July to December 2021), the number increased to 159 cases. During the Omicron-dominant period (since January 2022), there have been 185 reinfection cases, with 56 occurring between the 17th and 27th of this month.

[Image source=Yonhap News]

COVID-19 Variants Enter at Average Six-Month Intervals... 'Deltacron' Confirmed Overseas

Domestic COVID-19 variants have entered and become dominant at an average interval of six months. The Alpha variant was first detected in a UK entrant in December 2020, followed by the introduction of the Delta variant in April 2021. Eight months later, Omicron entered the country in December last year and quickly became dominant by the third week of January. The global variant epidemic followed a similar pattern, with Alpha, Beta, Gamma, Delta, and Omicron variants being discovered and becoming dominant at intervals of five to six months.

In Europe, where the Omicron wave has passed once, new variants are being reported. The World Health Organization (WHO) officially confirmed the 'Deltacron' variant, a recombinant of Delta and Omicron variants, on the 9th. Currently, small numbers of cases have been reported in France, Denmark, and other countries. There is no data yet analyzing the transmissibility or severity of the Deltacron variant. However, WHO and the UK Sanger Institute suggest that since the spike protein of Deltacron is derived from Omicron, infection with Deltacron may be preventable by antibodies generated through vaccination or prior Omicron infection. In Israel, a new variant combining Omicron and Stealth Omicron (BA.2) was reported on the 16th.

Professor Jung Jae-hoon of Gachon University’s Department of Preventive Medicine stated at the Korean Vaccine Society’s online academic conference on the 25th, "There is an average 30% chance each month that a COVID-19 variant will appear domestically," adding, "Due to the nature of infectious diseases and dynamic herd immunity, repeated resurgences are inevitable." According to foreign media, Dr. Chris Whitty, the UK government’s Chief Medical Officer, also predicted, "A variant worse than Omicron could emerge within two years."

Health authorities have also acknowledged the possibility of new variant emergence and introduction. At a briefing the previous day, Jeong Eun-kyung, Director of the Korea Disease Control and Prevention Agency, warned, "The possibility of new variant emergence is very high at any time," and added, "Although recombinant variants like Deltacron have not yet been confirmed domestically, given the large-scale epidemic ongoing in our country, the possibility remains at any time."

30% Monthly Probability of Domestic COVID Variant Emergence... 'Variant Surveillance' Needed

Experts emphasize the need for 'variant surveillance' and 'lifestyle changes' to prepare for COVID-19 variants. Professor Lee Hyuk-min of Severance Hospital’s Department of Laboratory Medicine said, "The problem lies in variants that evade existing immunity," adding, "Surveillance functions must be strengthened to quickly identify such variants." He explained that when there is a sudden surge in confirmed cases or deaths, or an increase in deaths among specific age groups?signs of a different infection pattern?whole genome sequencing should be conducted promptly to determine if a variant is involved.

Professor Lee also stated, "While quarantine measures to prevent variant spread are necessary, social distancing causes fatigue, so medium- to long-term lifestyle changes are needed," adding, "Facilities with ventilation should be expanded, the culture of group meals as a norm should be eliminated, and a culture of resting when sick should be established."

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