Normally, as we approach the end of the year, there are several things that we can expect from it, such as the incessant replay of Mariah Carey’s classic, and seemingly only song, “All I Want For Christmas”. Concurrently, however, in this new pandemic era, other than year-end travel restrictions, we are expecting the emergence of a new Sars-cov-2 variant or a new variation of an existing virus Covid-19. The latest one is the B.1.1.529 variant also known as variant Omicron, hereafter will be referred to as VO.
One could say that the emergence of VO is not too shocking, given that we have seen the emergence of other variants of the virus. Some of us might recall the emergence of variant Mu and its spread in many countries of South America and North America. Additionally, most of us can still remember horrors inflicted upon us by the uncontrollable spread of Delta variants.
Truth be told, other than these two “famous” variants, there are other variants of the SARS-CoV2. Perhaps you are wondering why some variants are more talked about compared to others. That’s probably because what is missing from the conversation is the process in which these variants are created and the results.
So how do viruses mutate, and why do they mutate? To put it simply, viruses mutate as they replicate. When our cells divide, they have to make multiple copies of all of our genetic materials and genetic information such as DNA, RNA, and other kinds of proteins to distribute to the new cells. During this production process, there are enzymes in our cells whose job is to check and make sure that the cells have correctly copied all the original genetic information. Due to this proofreading mechanism, the error rate that occurs when a human cell divides is very low (1 in 100,000) and an error occurs almost infrequently. This is not to say that NO error occurs because nothing is absolute in nature, but it’s just to illustrate that animal cells don’t accumulate mutation as often as viruses do.
How about viruses then? As viruses have to infect their hosts to replicate and spread, they’re dependent on having as fast a replication process as possible. Additionally, there are no such proofreading mechanisms in viral replication as there are in cellular replication. And when you’re working fast, usually you make more mistakes than when you work at a slower pace, especially if there’s no one to proofread your work. This is why mutations in viruses occur at a much higher rate compared to cellular mutations (1 in 1000 for viruses vs 1 in 100,000 for mammalian cells), and why so many new SARS-CoV2 variants show up in just two years of its identification.
The next question is if these mutations occur so often, are they all dangerous? The answer is no. Mutations usually confer three things to the virus: 1) Nothing, 2) something detrimental to the organism’s longevity or 3) something beneficial to the organism’s longevity. The type 1 mutation, or sometimes called “silent mutation” usually won’t result in anything different to the virus’ appearance or function. The second type of mutation will result in something bad for the virus, whether it impedes their virulency or actually kills the virus. This type of mutation usually won’t be inherited and passed down to the next generation of viruses since it’s not beneficial for their population. On the other hand, the third type of mutation is something that will be retained and passed down to the next generation of viruses because it helps the virus spread better and more efficiently.
The mutations that gave rise to the Delta and Omicron variants can be classified as the third type of the mutation as it significantly increased SARS-CoV2’s virulence. Additionally, they will likely be the dominant variants for years to come, as they will be the ones with superior infectivity and thus will be able to out-replicate the other variants. We have seen previously how fast Delta spread and how it’s become the dominant variant in many countries and it seems something similar might be the case with Omicron with its discovery in 25 countries in just one week of its initial discovery.
Based on the limited data we have so far there is potential that Omicron will spread even faster. Yet we still can’t firmly say whether Omicron will cause a more severe symptom compared to its predecessors. The limited data so far showed that the existing vaccines still work to protect against the more severe side effects of COVID-19 and that the patients that have contracted Omicron only showed mild symptoms. There are still much more studies that need to be done on Omicron and its infectivity. In the meantime, what we can do is keep enforcing health protocols such as wearing masks when outside and limiting our mobility so we can limit the spread of the virus. At the same time, to reduce our chances of contracting severe Covid-19 symptoms, getting vaccinated is also recommended, especially to those of us with comorbidities.
This year-end surprise of a new SARS-CoV2 variant might not be the end-of-the-year surprise we want, but it is, unfortunately, the one we were given. As an adaptable organism, we homo sapiens will be able to adapt to this new challenge Mother Nature has thrown in the gauntlet and we will thrive against it.
By: Lily Hikam
Ph.D. in Biomedical Science, University of California, Irvine, USA