BA.4.6 Variant Spreading in the US... Could It Become a Factor in the Resurgence?

[Asia Economy Reporter Kim Young-won] Recently, the BA.4.6 variant has been increasing overseas, especially in the United States, drawing attention as a potential factor for another global resurgence.

According to the Global Alliance for Vaccines and Immunization (GAVI) and others, BA.4.6 is a reclassified variant from BA.4, differing from the globally dominant BA.5 by seven amino acids. BA.4.6 is mostly similar to BA.4 but has a mutation in the spike protein at ‘R346T,’ which has been identified in other variants as related to immune evasion.

Some overseas studies also suggest that BA.4.6 may have immune evasion capabilities. A recent study by a research team at Peking University found that BA.4.6 evades the immune system better than BA.5. The UK Health Security Agency (UKHSA) also analyzed in its weekly report that initial estimates show BA.4.6 has a 6.55% fitness advantage over BA.5, allowing it to replicate faster.

BA.4.6 has recently been increasing its share in the United States. According to the U.S. Centers for Disease Control and Prevention (CDC), which compiled variant detection rates in the U.S. for the week ending on the 17th, BA.4.6 was detected at 10.3%, ranking just behind the dominant BA.5 at 84.8%. The detection rate of BA.4.6 in the U.S. increased weekly from 7.7% on August 20 to 8.5% on September 3, and 9.4% on September 10.

UK authorities are also monitoring BA.4.6 as its detection rate rises. According to the UKHSA, BA.4.6 was detected at 3.31% during the week of August 14?20, and as of September 6, a cumulative total of 1,697 cases had been recorded.

BA.4.6 has already entered South Korea, but unlike in the U.S., it is not showing an increasing trend. Since its first detection on July 7, a total of 24 cases have been confirmed: 11 in July, 8 in August, and 5 in September. Among these, 3 were domestic infections and 21 were imported cases. The detection rate of BA.4.6 in the first week of this month is 0.1%.

Currently, the domestic COVID-19 resurgence is clearly declining, but authorities have pointed to ‘new variants’ as a variable in the resurgence. On the 15th, Baek Kyung-ran, Director of the Korea Disease Control and Prevention Agency, stated, “Due to increased face-to-face contact during the Chuseok holiday, the decline in cases may temporarily stagnate or show a short-term increase, but unless there is a major change such as the spread of a new variant, the long-term downward trend is expected to continue.”

Experts say more observation is needed regarding the possibility of BA.4.6 becoming dominant domestically. Professor Kim Woo-joo of the Department of Infectious Diseases at Korea University Guro Hospital said, “In the U.S., where BA.5 is dominant, BA.4.6 is uniquely increasing. Although research on the immune evasion and transmissibility of BA.4.6 is still limited, we need to closely watch how the situation in the U.S. develops.”

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