The World Health Organization designated a "variant of concern"-sars-cov-2-variant-of-concern) after researchers in South Africa reported a new variant named Omicron. Omicron is the most heavily altered variant of the virus that causes COVID-19.
The Omicron variant has 50 different variations, with 32 different variations on the spikeProtein alone. The spike protein is found on the outside of the SARS-CoV-2 virus and it helps it get into cells.
The Delta variant has nine different genes. It is very concerning that the Omicron variant may be more transmissible or better at evading immune protection because of the larger number of mutations.
I study emerging and zoonotic viruses to better understand how they emerge. The COVID-19 virus has been studied by my research group.
Why are there new SARS-CoV-2 variant?
The Omicron variant has a high number of mutations and the emergence of another variant is not surprising.
Random mutations accumulate in any virus through natural selection. The process is sped up in the viruses. The variant will out-compete all other existing virus variants if a set of mutations provides a survival advantage.
Is the Omicron variant more dangerous and transmissible than Delta? We don't know. The conditions that led to the emergence of the variant are not yet clear, but what is clear is that the shear number and configuration of the Omicron is unusual.
One possible explanation for the emergence of viral variants with multiple genes is through a patient who has an immune system that is suppressed.
Some of the earlier versions of the disease, such as the Alpha variant, may have come from a patient. The Omicron variant is very different from all other strains, which raises questions about how it came about.
Another possible source of variant is through animal hosts. Animals can be affected by the COVID-19 virus, including tigers, cats, and dogs.
In a study that is not yet peer-reviewed, an international team that I lead recently reported widespread infections by the disease in free-living and captive white-tailed deer in the US. We can't rule out the possibility that the Omicron variant emerged in an animal host.
Delta is between 40 and 60 percent more transmissible than the Alpha variant, and nearly twice as transmissible as the original SARS-CoV-2 virus first identified in China. The Delta variant's heightened transmissibility is the primary reason why researchers believe it was able to out-compete other variant to become the dominant strain.
A key factor in viral fitness is how quickly a virus can make more copies of itself. A study estimated that the Delta variant produces 1,000 times more virus particles than its predecessors.
People with the Delta variant are making and releasing more virus, which is a potential mechanism for its increased ability to spread.
The Delta variant's increased ability to replicate is thought to be due to the fact that the spike protein is more efficient in binding to the host.
The Delta variant has acquired a new way to evade neutralizing antibodies that are critical to the body's defense against invading Viruses. Multiple reports have shown that the COVID-19 vaccines have been less effective against the Delta variant.
The Delta variant became successful because of a combination of high transmissibility and immune evasion.
The Delta variant has a higher risk of being hospitalized compared to the original SARS-CoV-2 and early variant.
The Delta variant's ability to enter cells and cause more severe disease is thought to be a result of the P681R mutation.
Will Omicron replace Delta?
It's too early to say if the Omicron variant will become dominant or if it will be a different story. Some of the Delta variant's quirks are also found in Omicron.
The Omicron variant has more than double the number of deletions in the binding domain of the spike protein compared to the Delta variant.
The combination of all the Omicron genes makes it more transmissible or better at immune evasion than Delta. We could see the spread of this variant around the world. It is possible that the high number of mutations could make the virus unstable.
The Omicron variant is unlikely to be the final variant and more will emerge. Natural selection and adaptation will result in more variant that could be more transmissible than Delta.
The process of viral adaptation never ends.
Lower vaccination rates in many countries mean that there are still a lot of people who are susceptible to the virus, and that it will continue to circulate as long as it can spread.
The emergence of the Omicron variant is a reminder that the vaccine is needed to stop the spread of the disease.
Professor of Emerging Infectious Diseases at Penn State.
The Conversation's article is a Creative Commons licensed one. The original article can be found here.
