"Stealth Omicron May Have Higher Infectivity and Cause More Severe Illness" ... Japanese Research Results

Stealth Omicron Becomes Dominant Strain in at Least 10 Countries

Omicron virus.
Photo by Yonhap News

[Asia Economy Reporter Na Ye-eun] A study has found that the 'Stealth Omicron' (BA.2), a subvariant of the COVID-19 Omicron variant, may have stronger transmissibility, severity, and ability to evade vaccines and treatments than the original Omicron (BA.1).

According to the US CNN broadcast on the 17th (local time), a research team led by Kei Sato from the University of Tokyo stated that Stealth Omicron appears to spread faster and cause more severe cases than BA.1. The results were published on the medical preprint site 'bioRxiv.org'.

The research team said, "Stealth Omicron has characteristics that allow it to evade immunity induced by vaccines, similar to BA.1, and it seems to have resistance to some monoclonal antibody treatments originally used for Omicron."

However, they added, "Receiving a booster shot restores the protective effect of the vaccine, reducing the risk of progressing to severe illness after infection by about 74%."

Researcher Saito said, "Based on the study results, Stealth Omicron should not be considered just a type of Omicron and requires closer monitoring," adding, "Since Stealth Omicron cannot be detected by existing Omicron testing methods, countries around the world must first establish detection methods for it."

Citizens are waiting in front of the screening clinic. The photo is not related to any specific expressions in the article.

Meanwhile, Dr. Daniel Rose of the Cleveland Clinic in Ohio, USA, said, "This study shows that Stealth Omicron may be a worse virus that spreads faster and causes more severe symptoms than BA.1."

Dr. Deborah Fuller of the University of Washington School of Medicine stated, "People infected with Omicron after vaccination seem to have some defense against Stealth Omicron," and added that Stealth Omicron is unlikely to lead to a more severe outbreak than BA.1.

She continued, "We are currently competing with the virus. We hope our immune system stays ahead of the next emerging variant, but we don't know if we are ahead," emphasizing, "In that sense, it is not yet time to lift mask mandates."

The WHO also warned countries worldwide, noting that while the spread of Omicron appears to be slowing in many regions, Stealth Omicron is increasing. According to the WHO, from the 7th to the 13th, the number of new COVID-19 cases worldwide decreased by 19% compared to the previous week, but Stealth Omicron continued to rise, accounting for over 20% of new cases.

Stealth Omicron is estimated to be 30-50% more transmissible than BA.1. It has been detected in 74 countries worldwide and in 47 states in the US. It has already become the dominant strain in at least 10 countries, including Asian countries such as China, India, Pakistan, Bangladesh, the Philippines, and Denmark.