Omicron Photo: VCG

A Chinese research team proved that Omicron's pathogenicity has decreased compared with the original strain of the coronavirus and its other variants, a year after WHO declared Omicron a variant of concern.

Pathogenicity and virulence of coronavirus variants are the key problems that Chinese scientists have been focused on. Recently a research team from the State Key Laboratory of Virology in Wuhan University conducted an experiment that shows that the pathogenicity of Omicron had dramatically decreased. 

Lan Ke, director of the laboratory, told the Global Times that his team found that Omicron has less ability to infect Calu-3 (a non-small-cell lung cancer cell) than the original strain, and the ability of duplicating cells is 10 times lower than the original.

During experiments on mice, Lan's team also found that infective doses of 25 to 50 of the original strain could kill a mouse, whilst it takes 2,000 infective doses of Omicron to kill a mouse. And the virus load in tested mice' lungs was 100 times lower than the original strain. 

Lan said that the results show that compared with the original strain, Omicron has weaker ability to cause diseases combined with a lower virulence. This reminds us not to panic about Omicron, and for ordinary people, the damage caused by coronavirus has markedly diminished compared to the original strain. 

Previously, a research paper published by scientists from the University of Hong Kong and Hainan Medical University in January this year showed that the replication of Omicron is substantially attenuated in human Calu3 and Caco2 cells. Moreover, the replication of Omicron is markedly attenuated in both the upper and lower respiratory tracts of infected mice compared with other variants, such as Delta. Compared with the original strain of the coronavirus and previous variants such as Delta and Beta, infection by Omicron causes the lowest reduction in body weight and the lowest mortality rate.

This month, Neeltje van Doremalen from the Laboratory of Virology, National Institute of Allergy and Infectious Diseases, National Institutes of Health of the US published a paper with other scientists which shows that rhesus that were infected with Omicron shows lower symptoms than those with Delta, and animals inoculated with Omicron BA.1 or BA.2 shed less virus and have a lower virus load in the lower respiratory tract than rhesus macaques infected with the Delta variant.

Global Times