Korea CDC: Omicron causes lower mortality than Delta

Research by the Korea Centers for Disease Control and Prevention (KCDC) shows that the risk of severe disease or death after Omicron infection is 75% lower than Delta’s.

Scientists analyzed data on about 67,200 cases of the virus since December 2021. They found the severity and mortality after Omicron infection to be 0.38% and 0.18%, respectively. This figure is lower than 1.4% and 0.7% in Delta cases.

According to the KDCA definition, F0s are considered severe when treated in the intensive care unit (ICU). Thus, only 0.18% of people infected with Omicron had to be in the ICU compared to 1.4% in Delta.

The study found that 56% of the 1,073 people who died from Covid-19 in the past 5 weeks were not vaccinated or received only one dose of the vaccine. People aged 60 and over accounted for 94% of the deaths.

The Omicron mutation caused the number of daily new infections in South Korea to hit a record high of more than 100,000 last week. Authorities eased social distancing because of lower death rates. Vaccinated people exposed to F0 do not need to be isolated, prioritizing diagnosis and treatment at home to free up medical resources. Restaurants are allowed to open more than an hour later, accepting up to 8 diners.

The KDCA said that Omicron has become the dominant strain in Korea since January. Since the first week of February, 90% of new cases are Omicron.

Scientists have recently been concerned about Omicron’s sub-lineage, BA.2. Previous Japanese research in the laboratory on mice showed that BA.2 can cause more severe symptoms than Delta. BA.2 has the ability to evade vaccine-induced immunity. It is resistant to several treatments, including the drug sotrovimab, a monoclonal antibody.

People line up at a testing site in South Korea, February 10. Photo: Reuters

BA.2 can replicate itself in cells faster than BA.1, the original version of Omicron. It also binds cells more efficiently. This allows the virus to make larger clumps of cells (called syncytial cells) than BA.1. The syncytial masses later become the “factory” for the production of viral copies. This is inherently a feature of Delta. Experts say that’s why the virus wreaks havoc on the lungs so aggressively.

However, on February 23, the World Health Organization (WHO) said that the subtype BA.2, caused no more severe symptoms than the original Omicron version.

WHO chief scientific officer, Maria Van Kerkhove, said: “We did not see any difference in the severity of BA.2 from BA.1 (the original version of Omicron). They cause symptoms and an increased risk of entry. This information is really important, because in some countries both BA.1 and BA.2 are highly contagious.”

Thuc Linh (According to CNA)


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