‘Stealth’ version of the Omicron variant identified

A new type of the Omicron coronavirus variant, which is undetectable by PCR tests, has been identified. A person infected with the so-called “stealth” version of the Omicron variant will be tested positive for COVID-19, but the current PCR tests cannot tell whether the virus is a variant or not, which is why governments and health authorities around the world have become tensed up.

The Guardian and The Financial Times reported that scientists have found a “stealth” version of Omicron, which is harder to distinguish from other variants using COVID-19 PCR testing method. Global health authorities have so far determined that when the test does not detect the spike protein, one of the COVID-19 viral genes, a variant is highly likely to be the Omicron variant. The World Health Organization also recognized this method of detecting mutations of the spike protein, helping identification of a sample that is highly likely to be the Omicron variant.

However, the newspapers further reported that the “stealth” version of the Omicron variant does not have such a mutational trait, making it difficult to distinguish it from other variants. To confirm‎ whether a variant is Omicron, whole genome sequencing technique is deployed; however, it is not only time-consuming but also unfeasible as such technique cannot be deployed on all probable samples tested positive for coronavirus.

If the new variant “stealth Omicron” spreads in poor countries, researchers point out, infection control will be much more difficult. Paul Kellam, professor of viral genomics at Imperial College London, said the countries dependent on PCR assays targeting the spike protein will have difficulty in tracking the Omicron variant.

More than seven cases of the Omicron variant have been reported in countries including South Africa, Australia, and Canada. However, scientists have yet to find about the variant’s transmissibility, virulence, and whether it is protected by immunity from vaccines. Some scientists suggested to split the existing Omicron into BA.1 (standard Omicron) and BA.2 (the newer “stealth” variant). Prof Francois Balloux of the University College London Genetics Institute said that BA.1 and BA.2 are quite differentiated genetically, and the two lineages may behave differently.


Jong-Yeob JO jjj@donga.com