First Omicron science

Viral replication is reduced in the lung tissue, but increased in the bronchi. This could indicate increased transmissibility but reduced pathogenicity.

Link for free download of John's two text books,

Campbell's Pathophysiology Notes, Amazon orders for the UK,

Campbell's Physiology Notes

First video on my series on the respiratory system,

HKUMed finds Omicron SARS-CoV-2

can infect faster and better than Delta

in human bronchus

First information on how Omicron SARS-CoV-2 infect human respiratory tract.

Omicron infects and multiplies 70 times faster than the Delta in human bronchus,

which may explain why Omicron may transmit faster

Omicron infection in the lung is significantly lower than the original SARS-CoV-2,

which may be an indicator of lower disease severity.

This research is currently under peer review for publication.

Pioneered the use of ex vivo cultures of the respiratory tract,

for investigating many emerging virus infections since 2007

Lung tissue removed for treatment of the lung

Dr Chan and his team successfully isolated the Omicron SARS-CoV-2,

and used this experimental to compare infection with the original and Delta variants

24 hours after infection

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 disease.

Dr Chan

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, taken together with our recent studies showing that the Omicron variant can partially escape immunity from vaccines and past infection,

the overall threat from Omicron variant is likely to be very significant.

Koch's postulates

The microorganism must be found in abundance in all organisms suffering from the disease but should not be found in healthy organisms.

The microorganism must be isolated from a diseased organism and grown in pure culture.

The cultured microorganism should cause disease when introduced into a healthy organism.

The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.