Unexpected Dominance of COVID Variant Unforeseen by Experts... Could It Become a Spread Factor?

BQ.1, BQ.1.1 'BQ Hyeongje' accounts for 1-3% domestically
Domestic BN.1 spread faster than in the US

On the 27th, citizens who visited the temporary screening clinic at Seoul Station Plaza were waiting to get tested. Photo by Hyunmin Kim kimhyun81@

[Asia Economy Reporter Byun Seon-jin] Amid the 7th wave of COVID-19, new variants are competing fiercely, and the BN.1 variant, which experts did not anticipate, is rapidly gaining dominance. While various variants excluding the dominant BA.5 in Korea have been competing with a 1-3% share, BN.1, derived from BA.2.75, has recently surged to around 7%. In Korea, it was widely expected that BQ.1 and BQ.1.1, which spread rapidly in the US and Europe, would surpass BA.5, which led the previous summer wave, and become the dominant variants this winter.

According to the Korea Disease Control and Prevention Agency (KDCA) on the 29th, during the 3rd week of this month (November 13-19), the detection rate of the Omicron subvariant BA.5 dropped to 79.5%. BA.5, which held an overwhelming dominance of 99% in the first week of September, has gradually decreased below 80%. The subvariants of BA.5, BQ.1 and BQ.1.1, accounted for only 1.5% and 3.1%, respectively. BQ.1’s share fell by 0.7 percentage points from 2.2% the previous week. The so-called 'BQ brothers,' BQ.1 and BQ.1.1, ranked first and second in the US as of the 4th week of this month, with shares of 29.4% and 27.9%, respectively, having displaced BA.5 as the dominant variant on the 26th (local time). Domestic health experts had identified the BQ brothers as the likely dominant variants leading Korea’s 7th wave, but they have not gained traction. Other variants such as BF.7 (1.7%), BA.2.75 (1.6%), and XBB.1 (1.2%) remain at shares between 0-1%.

The BQ brothers were expected to lead the 7th wave... Unexpected results

Meanwhile, BN.1’s share jumped from 4.9% the previous week to 7.6%, showing prominence. BN.1 is a subvariant of BA.2.75, known for its high transmissibility at the time of discovery, and has been identified in 37 countries including the US, UK, Denmark, and India. Both the US and Korea began detecting BN.1 from September. A KDCA official from the New Specimen Analysis Division said, “Information on BN.1’s infectivity is still lacking, but experts predict it to be a variant with strong immune evasion.” Professor Baek Soon-young, emeritus at the Catholic University Medical School, also noted, “Since BN.1 is a subvariant of BA.2.75, it has sufficient potential to spread more rapidly.” The US Centers for Disease Control and Prevention (CDC) reported that “BN.1 is estimated to double every two weeks in the US.”

[Provided by Korea Disease Control and Prevention Agency]

Professor Kim Woo-joo, an infectious disease specialist at Korea University Guro Hospital, said, “Variants that spread in the US and Europe have become dominant in Korea with a time lag, so we expected the BQ brothers to become dominant,” but added, “It is surprising that the BN.1 variant, which is spreading mainly in the western US states such as California and Florida, is being detected more rapidly in Korea.” According to the US CDC, the detection rate of BN.1 locally was 2.0% in the 2nd week of November, 2.5% in the 3rd week, and 2.9% in the 4th week, gradually expanding its territory. Professor Kim analyzed, “The resumption of daily life and the lifting of mandatory PCR (polymerase chain reaction) testing upon entry in October likely contributed significantly to increased overseas travel.”

Fatality rate is lower than early stages but reinfection is relatively easier... "Vaccines will still be effective"

[Image source=Yonhap News]

Since BN.1 is also a type of Omicron variant, its fatality rate is lower compared to early COVID-19. However, the problem is that it is likely to strongly evade vaccines designed for optimal variants. The updated vaccines currently administered in Korea target the original Wuhan strain, BA.1, and BA.4·BA.5. People who have immunity from COVID-19 infection are also relatively vulnerable to new variants. Professor Kim diagnosed, “People infected with variants that circulated between February-April or July-September may also be reinfected with the BN.1 variant.”

For this reason, even if the recent increase in COVID-19 cases slows down, if a dominant variant becomes clear, it could be a factor in further spread. Experts emphasize that while breakthrough infections cannot be ruled out, the effectiveness of vaccination remains. Professor Baek Soon-young said, “When a new variant appears, it’s not that the current updated vaccines are ‘fine-tuned’ (fine tuning) for it, but since BN.1 is a subvariant of Omicron, the overall preventive effect is sufficient.”