[Issue Q&A] 'Omicron' Transmission and Fatality Rates All Unclear... "It Will Take Weeks to Confirm Its Identity"

Increased Infectivity and Immune Evasion
Massive Spike Mutations Confirmed

Difficult to Detect with Domestic PCR Tests
Separate PCR Development Planned

Potential Neutralization of Existing Antibody Treatments
Oral Treatments Likely to Remain Effective

[Image source=Reuters Yonhap News]

[Asia Economy Reporter Lee Chun-hee] On the 26th (local time), the World Health Organization (WHO) recognized the Omicron variant as a ‘variant of concern (VOC)’ following the Alpha, Beta, Gamma, and Delta COVID-19 variants, and it is now threatening the world. Countries around the globe are quickly shutting their borders to African countries where the Omicron variant has been detected, including South Africa. Although it is estimated that the Omicron variant spreads much faster than previous variants, more time is needed to determine how deadly it is.

Q. What differences does the Omicron variant have compared to previous variants?

A. The risk posed by the Omicron variant is not yet clear. However, since it has more than 50 mutations across its entire genome and 32 mutations in the spike protein?the part that binds to human cells?it is suspected that its transmissibility and immune evasion capabilities have increased significantly. This is about twice the number of spike protein mutations found in the Delta variant, which is currently dominant in South Korea.

Notably, the Omicron variant has a large number of spike protein mutations that were previously studied and linked to increased infectivity and immune evasion in the Alpha, Beta, Gamma, Delta, and Lambda variants. This is why the WHO designated it as a major variant just three days after South Africa reported it on the 24th.

Q. How dangerous is it?

A. Some claim that the Omicron variant is about six times more dangerous than the Delta variant, which has become dominant in many countries due to its high transmissibility and immune evasion. Ulrich Elling, a molecular biologist at the Austrian Institute of Molecular Biotechnology, analyzed preliminary data and suggested that Omicron’s transmissibility could be 500% higher than Delta’s. Similar observations about Omicron’s higher transmissibility have been made in the United States, the United Kingdom, and other countries.

However, the WHO, while recognizing Omicron as a variant of concern, remains cautious about its specific risks. In an ‘Omicron update’ on the 28th, the WHO stated, "It is not yet clear whether Omicron is more transmissible than other variants, nor whether it causes more severe disease." Regarding the increase in hospitalization rates in South Africa, the WHO noted that this might be due to the overall rise in COVID-19 cases rather than the result of Omicron infections specifically, and it may take several weeks to fully assess the risk posed by the Omicron variant.

Excessive mutations might even hinder the spread of the virus. In Japan, where new cases have recently dropped sharply, the concept of a ‘Delta self-destruction theory’ has been proposed. This theory suggests that continuous mutations in the Delta variant have led to changes that actually inhibit viral replication.

On the morning of the 28th, medical staff are conducting COVID-19 testing at the screening clinic of Songpa-gu Public Health Center in Seoul. [Image source=Yonhap News]

Q. It is said that detecting the Omicron variant domestically is impossible. Why?

A. This is due to the characteristics of the domestic polymerase chain reaction (PCR) tests. Typically, four target genes are analyzed to confirm COVID-19 infection: spike protein (S), envelope (E), RdRp, and nucleocapsid protein (N). As of July, 26 PCR diagnostic products approved in South Korea mostly target the E, RdRp, and N genes to amplify and confirm infection and variant status. Only three products target the S gene.

Currently, overseas, if PCR tests detect other targets but fail to detect the S gene, genomic sequencing or whole genome analysis is used to confirm the presence of the Omicron variant. However, since domestic PCR tests do not target the S gene, initial detection is difficult. Therefore, health authorities plan to develop and distribute a separate PCR test capable of identifying Omicron.

Q. Are vaccines and treatments effective?

A. Among treatments, existing antibody therapies are likely to be rendered ineffective. Antibody treatments work by binding antibodies to the spike protein to block its attachment to human cells, so mutations in the spike protein can make these antibodies useless, necessitating the development of new antibodies.

However, oral antiviral treatments developed by Merck and Pfizer work by inhibiting viral replication itself, so they are expected to remain effective despite mutations.

Vaccines activate both antibodies that block spike protein binding and immune cells that directly attack COVID-19 infected cells. Although their effectiveness may be somewhat reduced, preventive effects are expected to be maintained. Vaccine developers such as BioNTech and Moderna have begun developing vaccines targeting Omicron and plan to release experimental vaccines within 2 to 3 months.