Double-ling on Weekends... Is a Double-Peak Trend Coming Amid Successive Variants?

40,000+ Daily on Saturday and Sunday, Highest in 10 Weeks
Before BA.5 Wave Peaks
More Contagious BA.2.75 Emerges

The Omicron subvariant BA.5, known for its strong transmissibility and immune evasion, is rapidly spreading, pushing the number of new COVID-19 cases over 40,000 even on weekends, marking the highest level in 10 weeks. Health authorities and experts initially predicted that if BA.5 became the dominant strain with a detection rate exceeding 50%, daily cases could reach between 200,000 and 290,000 as early as early August. However, the recent confirmation of the so-called 'Centaurus (BA.2.75)' variant, which is known to have even higher transmissibility, in South Korea has raised warnings that the ongoing spread of BA.5 combined with this new variant could further worsen the epidemic situation.

'Doubling' Continues Even on Weekends

According to the Central Disease Control Headquarters on the 18th, the number of new cases the previous day was 40,342, following 41,310 on Saturday (16th), marking two consecutive days with over 40,000 cases. This is the highest count in 12 weeks for a Sunday since April 24 (64,695 cases) and the highest for a Saturday in 11 weeks since April 30 (43,275 cases). Reflecting the weekend effect, the number of cases at midnight on that day was 26,299, which is 2.07 times higher than last week (11th) at 12,681 and 4.20 times higher than two weeks ago (4th) at 6,248. On a Monday basis, this is the highest number in 12 weeks since April 25 (34,361 cases).

Looking at weekly data, the cumulative number of cases from the 11th to the 17th was 250,003, which is 2.04 times the previous week (12th to 10th, 122,220 cases) and 3.93 times higher than two weeks ago (63,642 cases). As a result, South Korea ranks within the top 10 globally in both daily and weekly new cases. According to the international statistics site Worldometer, as of the previous day, South Korea ranked 8th among 208 countries in weekly new cases. The daily new cases also ranked 7th globally as of the 15th, a weekday.

The BA.5 variant is driving this surge. The detection rate of BA.5 among new cases in South Korea increased from 0.3% in the first week of June to 7.5% in the fourth week, reaching 24.1% in the last week. During this period, the detection rate among imported cases surged from 12.8% to 49.2%, and in July, it soared to 70.0%. In the first week of July, combining domestic and imported cases, the BA.5 detection rate was 35.0%, and health authorities expect the share of BA.5 to continue rising for the time being.

A Second Resurgence Possible

The problem is that the peak of the BA.5 wave has not yet been confirmed, and the more transmissible BA.2.75 variant has emerged. Experts explain that since the first BA.2.75 case had no history of overseas travel, it is highly likely that the variant has already spread within the community. Professor Eom Jung-sik of the Department of Infectious Diseases at Gachon University Gil Medical Center said, "The fact that the first confirmed BA.2.75 infection in South Korea had no overseas travel history means this variant has already entered the country," adding, "Whichever variant?BA.5 or BA.2.75?has stronger transmissibility is likely to become the dominant strain."

Depending on the spread of BA.2.75, three major scenarios are anticipated. The most likely is that BA.5 and BA.2.75 will spread simultaneously or sequentially. During the Omicron wave, BA.2 quickly replaced BA.1 in South Korea, resulting in a larger single-peak wave than initially predicted, whereas in the UK and other countries, BA.2 influenced the epidemic after the peak of BA.1, causing a double-peak wave.

Professor Kim Tak of the Department of Infectious Diseases at Soonchunhyang University Bucheon Hospital explained, "Considering that it took about four weeks for BA.2 to exceed 5% detection and another four weeks to surpass 50%, BA.2.75 is likely to lead to a double-peak wave in South Korea," adding, "Either way, this means the size or duration of the sixth wave will be extended." Jeong Ki-seok, Chair of the National Infectious Disease Crisis Response Advisory Committee, predicted, "If BA.2.75 shows high transmissibility following BA.5, it could surpass the previous domestic record of 620,000 new cases."

BA.2.75, confirmed to have entered the country, could also be outcompeted by BA.5. This would be similar to the case of BA.2.12.1, which entered South Korea in early May but failed to have a significant impact and eventually faded out. However, Professor Kim added, "Given that BA.2.75 has been detected in several countries even during the BA.5 wave, the likelihood of this scenario is relatively low."

There is also a possibility that BA.2.75 may show sluggish spread initially but cause a resurgence early next year when immunity from the sixth wave and vaccines wanes.

Health authorities state that while BA.2.75 may spread within communities, they will monitor whether it becomes the dominant variant without additional immediate measures. The government plans to secure 4,000 additional hospital beds in preparation for a scenario with 300,000 cases and to import treatment drugs sufficient for 940,000 people by the first half of next year, while also aiming to secure up to 10,000 medical personnel.

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