COVID 19: Why Omicron Variant Is Less Severe Than Others |READ DETAILS

New animal studies has revealed  the Omicron variant of COVID-19 could be less severe because it does not readily multiply in the lung tissue.

According to the studies, while the other COVID-19 variants usually damaged the lungs of patients quickly, the Omicron variant is milder in the way it attacks the lungs.

As reported by Nature – a monthly peer-reviewed medical journal on Thursday, early indications from studies conducted in South Africa and the United Kingdom signal that the fast-spreading Omicron variant of the coronavirus SARS-CoV-2 is less dangerous than its predecessor Delta.

The laboratory studies indicated that the Omicron variant does not infect cells deep in the lungs as readily as it does those in the upper airways.

“It’s a very attractive observation that might explain what we see in patients,” says Melanie Ott, a virologist at the Gladstone Institute of Virology in San Francisco, California, who was not involved in the research. But she adds that Omicron’s hyper-transmissibility means that hospitals are filling quickly — despite any decrease in the severity of the disease it causes.

Recall that the South African health authorities had announced on December 30 that the country had passed its Omicron peak without a major spike in deaths.

Similarly on December 31, a United Kingdom government report said that people in England who were infected with the Omicron variant were about half as likely to require hospitalisation or emergency care as were those infected with Delta.

The Nature report, however, stated further that the number of people who have gained immune protection against COVID-19 through vaccination, infection, or both has grown over time, making it difficult to determine whether the Omicron variant intrinsically causes milder disease than earlier variants.

To understand the new variant, Michael Diamond, a virologist at Washington University in St. Louis, Missouri, and his colleagues infected hamsters and mice with Omicron and other variants to track disease progression.

The differences were staggering after a few days, the concentration of virus in the lungs of animals infected with Omicron was at least ten times lower than that in rodents infected with other variants. Other teams have also noted that compared with previous variants, Omicron is found at reduced levels in lung tissue.

Diamond says he was shocked to see that the Omicron-infected animals nearly maintained their body weight, whereas the others quickly lost weight — a sign that their infections were causing severe disease.

“Every strain of SARS-CoV-2 has infected hamsters very easily, to high levels,” Diamond says, “and it’s clear that this one is different for hamsters.”

According to experts, the lungs are where the COVID-19 does much of its damage as lung infections often lead to tissue scarring.

Another group of researchers also found that Omicron is less successful than previous variants at infecting lung cells and miniature lung models called organoids.

The difficulty with Omicron entering lung cells could help to explain why it does better in the upper airways than in the lungs, says Ravindra Gupta, a virologist at the University of Cambridge, UK, who co-authored one of the TMPRSS2 studies, Nature reported.

This theory could also explain why, by some estimates, Omicron is nearly as transmissible as measles, which is the benchmark for high transmissibility, says Diamond. If the variant lingers in the upper airways, viral particles might find it easy to hitch a ride on material expelled from the nose and mouth, allowing the virus to find new hosts, says Gupta.

Although there is still much to learn about the new variant, Gupta says that fears raised in late November by the multitude of mutations in Omicron’s genome have not been completely borne out.

He said that the initial alarm offers a cautionary tale, noting that it is difficult to predict how a virus will infect organisms from its genetic sequence alone.

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