Hong Kong University finds Omicron SARS-CoV-2 infects 70 times faster than Delta

Dec. 16, 2021

A study led by researchers from the Li Ka Shing (LKS) Faculty of Medicine at The University of Hong Kong (HKUMed) provides the first information on how the novel Variant of Concern (VOC) of SARS-CoV-2, the Omicron SARS-CoV-2 infects the human respiratory tract.

Researchers found that the variant multiplies 70 times faster in the human bronchus than the Delta variant or the original strain of SARS-CoV-2. This may explain why Omicron seems to transmit faster between humans than previous variants.

The study also suggests Omicron causes milder infection in the lungs than the original SARS-CoV-2. This may be an indicator of lower severity of the disease, overall. The research is currently under peer review for publication

HKUMed researchers pioneered use of ex vivo cultures of the respiratory tract for investigating emerging virus infections such as avian influenza and coronavirus of the Middle East Respiratory Syndrome (MERS). The technique has been used since 2007, and is being applied to understand why the Omicron variant may differ in transmission and disease severity from other SARS-CoV-2 variants, according to a press release from HKUMed.

The method uses lung tissue removed for treatment of the lung, which is normally discarded, for investigating viral disease of the respiratory tract. Dr Chan and his 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.

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