On January 20th, the first COVID-19 patient has been confirmed in the state of Washington in the United States. Since then, COVID-19 has been transferring from people to people at a terrifying rate, and it was only about two months later that the United States has reached the highest number of cases in the entire world. Although many scientists in the US are racing towards finding an appropriate vaccine, it cannot be denied that many people are worrying about COVID-19 being sporadic – in other words, behaving similarly to flu seasons every year.
To demystify this mystery scientists must study mutations. Mutations are changes in the genetic coding of organisms, and in the context of viruses, although they can be so small that it is almost negligible, they can also be a serious problem that changes the entire course of vaccines.
How has the SARS-CoV-2 mutating?
Unfortunately, scientists suspect that SARS-CoV-2, virus responsible for the ongoing pandemic COVID-19 have been mutating throughout the course of the pandemic. If that is the case, it becomes extremely crucial to know how has the viruses have been mutating, and what patterns there are. Researchers in Europe also had the same question. They wanted to study how this virus has been changing starting from the very beginning of the pandemic. To do this, they collected over 7,000 different assemblies across the planet that would be used for comparison. If you look at the picture below, you can see that the assemblies were from the Americas, Europe, Asia. Africa, and more.
Figure 1. Map of acquired SARS-CoV-2 genomes. Adapted from “Infection, Genetics, and Evolution,” by L. van Dorp et al., 2020, Retrieved from PubMed. Copyright 2020 by Elsevier B.V..
Weak evidence of a rapid, widespread mutation
By comparing the collected assemblies against each other, scientists have developed a complex global phylogenetic tree and noticed that the virus indeed has been changing throughout the course of the pandemic. However, many of these mutations were neutral changes, and in fact, none of the mutations affected the phenotype of the SARS-CoV-2 virus at all. On the other side, researchers did find something very interesting regarding the mutations of the virus. Take a look at the regional phylogenetic tree below.
Figure 3. Global phylogenetic tree grouped. Adapted from “Infection, Genetics, and Evolution,” by L. van Dorp et al., 2020, Retrieved from PubMed. Copyright 2020 by Elsevier B.V..
Notice any patterns? When scientists have grouped the assemblies from the same region together, they were actually placed in places quite similar to each other rather than in disperse locations. For example, in the USA, the purple dots are placed relatively close to each other, indicated by the purple arrow. The same thing occurred for UK, Iceland, and even China – to researchers, this indicated that the these virus strains behaved almost like local epidemics, which were introduced independently to their respective regions. Although the virus may be changing slowly and slightly, the data suggests that there are still different types of the virus strains across the globe.
Why little change?
Scientists suspect that the reason why the SARS-CoV-2 has been mutating so slowly compared to the flu virus is that they did not face the pressure to do so. These virus strains perhaps did not face the strong pressure of natural selection yet. This is hopeful news for scientists around the globe: if the virus didn’t change their behavior nor their phenotype greatly, it means that a possible vaccine may be near. In fact, the CDC has declared to public state officials on September 2nd for public state health centers to start preparing for possible vaccination as early as late October (Source: CNN). Vaccination may be near, however, until then, it is important for all people – across the globe – to practice social distancing to prevent any further spread of the novel coronavirus.
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