‘Omicron’ variant of SARS infects lungs less but spreads more, says study

admin December 20, 2021
Updated 2021/12/20 at 3:03 PM

The Omicron variant of SARS-CoV-2 infects and multiplies quicker in the human bronchus than the Delta and original SARS-CoV-2 variants, which might explain why it spreads faster amongst individuals. However, it is difficult to infect the lower lungs, which experts believe may explain why incidences of severe illness are proportionately lower in Omicron patients.

Researchers from the University of Hong Kong’s LKS Faculty of Medicine led the investigation.

The two bronchi, which divide like a “y” into each lung, are located at the end of the windpipe. However, the scientific article, which is currently being peer reviewed, does not explain why the virus had a harder time spreading deeper into the lungs than prior variants.

The researchers investigated viral infections of the respiratory system using lung tissue retrieved for lung therapy, which is generally discarded. They compared infection with the original SARS-CoV-2 from 2020, the Delta variant, and the Omicron variant after isolating the Omicron SARS-CoV-2 variant. Over the course of 24 hours, Omicron replicated 70 times faster than the Delta variant and the original SARS-CoV-2 virus. The Omicron variant, on the other hand, replicated in lung tissue less effectively (more than 10 times less) than the original SARS-CoV-2 virus.

Scientists engaged in the research, however, acknowledged this was insufficient cause to relax. In a press statement, Dr. Michael Chan Chi-wai, Associate Professor, School of Public Health, HKUMed, and the study’s leader, said, “It is important to note that the severity of disease is determined not only by virus replication but also by the host immune response, which may lead to dysregulation of the innate immune system, or cytokine storm.”

Even though the virus itself is less harmful, a highly infectious virus might cause more severe sickness and death by infecting a large number of individuals. As a result, when combined with our previous findings that the Omicron variation may partly evade vaccination and infection-induced immunity, the total danger posed by the Omicron variant is likely to be severe.

At least 73 cases of the Omicron variant have been reported in India, and data from research in South Africa, which has witnessed the largest spike in Omicron cases, shows that at least a fourth of roughly 78,000 positive cases were of the Omicron variant. Recent laboratory tests have also shown that people who were vaccinated developed 20–40 times fewer antibodies against Omicron than those who were vaccinated with previous variants. Those who had been vaccinated and had previously been exposed to the virus had the greatest antibody levels.

So far, roughly 10,000 cases of Omicron have been reported in the United Kingdom, with at least ten individuals hospitalised. One individual died after contracting the variant, which is expected to become the prevalent strain. Currently, the country is reporting about 80,000 cases each day. Daily case counts in India had dropped below 5,000 per day, but had suddenly risen to over 7,000 on Thursday, with around 3,500 cases recorded from Kerala. The Delta and its derivatives are said to be involved in the majority of these.

The discoveries were an “interesting twist,” according to Anurag Agrawal, Director of the CSIR-IGIB, who was directly engaged in the sequencing of SARS-CoV2 variants. When compared to ancestral SARS CoV2/Delta, Omicron infects and multiplies better in the airways than in the lung. “This might be milder—more like an upper respiratory infection or a common cold than pneumonia—but I still consider the risk to be significant.”


Source: The Hindu

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