In a new study from the University of Hong Kong, researchers found new evidence on how the omicron SARS-CoV-2 infects the human respiratory tract.
They found that omicron SARS-CoV-2 infects and multiplies 70 times faster than the delta variant and original SARS-CoV-2 in humans, which may explain why omicron may transmit faster between humans than previous variants.
They also showed that the omicron infection in the lung is much lower than the original SARS-CoV-2, which may be an indicator of lower disease severity.
In the study, the team aimed to understand why the omicron variant may differ in transmission and disease severity from other SARS-CoV-2 variants.
Their new method uses lung tissue removed for treatment of the lung, which is normally discarded, for investigating virus diseases of the respiratory tract.
The team successfully isolated the omicron SARS-CoV-2 variant and used this experimental model to compare infection with the original SARS-CoV-2 from 2020, the delta variant and the recent omicron variant.
They found that the novel omicron variant replicates faster than the original SARS-CoV-2 virus and delta variant in the human bronchus.
At 24 hours after infection, the omicron variant replicated around 70 times higher than the delta variant and the original SARS-CoV-2 virus.
In contrast, the omicron variant replicated less efficiently (more than 10 times lower) in the human lung tissue than the original SARS-CoV-2 virus, which may suggest lower severity of the disease.
The team says it is important to note that the severity of disease in humans is not determined only by virus replication but also by the host immune response to the infection, which may lead to dysregulation of the innate immune system, i.e. “cytokine storm”.
It is also noted that, by infecting many more people, a very infectious virus may cause more severe disease and death even though the virus itself may be less pathogenic.
Therefore, the findings suggest that the omicron variant can partially escape immunity from vaccines and past infection, the overall threat from the omicron variant is likely to be very significant.
If you care about COVID, please read studies about when is it OK to take a rapid antigen test for COVID, and findings of COVID-19 pills that may change everything.
For more information about health, please see recent studies about who has the highest risk of heart damage in COVID-19, and results showing that Omicron may be less likely to cause severe disease.
One researcher of the study is Dr. Michael Chan Chi-wai.
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