Emerging of SARS-CoV-2 Variants: Are they dangerous?
Last Updated 5 February 2021. Cellspect Co., Ltd.
In just about one year, the novel coronavirus has infected more than 100 million people and took away more than 2 million lives. Before the pandemic subsided, several virus variants appeared recently, causing panic among most people.
As the Covid-19 pandemic developed, numerous groups of scientists around the world have been sequencing isolates and uploading them to the GISAID (Global Initiative on Sharing All Influenza Data) database in a global collaborative effort to compile SARS-CoV-2 genetic sequences. This enables tracking of new variants that emerge over the course of the pandemic. By January 2021 as many as 300,000 genetic variants of SARS-CoV-2 have been identified. The mutation number looks scary, but it is actually very normal in all RNA viruses because it is part of their natural life cycle. SARS-CoV-2 mutates and acquires about one new mutation in its genome every two weeks but the majority of new variations in the SARS-CoV-2 genetic code have little effect on the virus. Most variants just disappeared silently.
However, there are some notable variants worth experts’ concerns. The virus first detected in Wuhan, China, is not the same one you will find in most corners of the world. The variant D614G, named because the amino acid aspartate (D, in biochemical shorthand) at the 614th position of the spike protein was replaced by glycine (G), emerged in Europe in February and became the globally dominant form of the virus. D614G also correlates with the symptom of loss of smell which may result from higher binding of the RBD to the ACE2 receptor and hence higher infectivity of the olfactory epithelium. Another, called A222V, spread across Europe and was linked to people's summer holidays in Spain. And now, new variants, B.1.1.7 from UK, B.1.351 from South Africa, and P.1 from Brazil emerged in the fall of 2020.
The new variants caused alarm because all of them involved multiple mutations including mutations in the receptor binding domain (RBD) of the spike protein. It is known that the novel coronavirus attaches to human cells through a "spike protein." After the spike protein binds to the ACE2 receptor on a human cell, the viral membrane fuses with the human cell membrane, allowing the genome of the virus to enter human cells. The RBD mutation of the virus is the reason for the higher affinity of SARS-CoV-2 and ACE2.
Preliminary reports show that British variant B.1.1.7 is more transmissible than previous circulating viruses, with an estimated increase of between 50% and 70% in transmissibility. The mutant N501Y which is found in all three emerging variants, increase binding affinity between virus and cells thus makes the virus bind more tightly to human cells.
More infectious doesn’t mean more dangerous. At present, there is no data that British variant increases severity of Covid-19. On January 22, British Prime Minister Boris Johnson stated that "British coronavirus variant may be more deadly", however, later the UK government revised its original view that the B.1.1.7 variant was not more dangerous. The government said that new evidence showed that on average, for 1,000 men in their 60s, 13 to 14 would die if they contracted the new variant, compared to 10 for the original strain of SARS-CoV-2. However, even if the effect of the variant on severity does not change, if it spreads much more easily, that means the quality of medical care may drop, which can lead to higher death rates than would otherwise be expected.
Another concern is that if vaccines and current drugs still work against the new variants. Both Pfizer and Modena stated that their laboratory tests showed their vaccine still work against the new variants. Regeneron also reported that their antibody cocktail treatment can neutralize variants, despite the mutations. Although more evidence is needed, experts generally believe that vaccines and drugs will still be effective so far.
To sum up, the best way to face these variants is to stay alert but no need to panic. New variants still spread the same way as the ordinary form of the coronavirus. That means everyone should do the same things: washing hands, physical distancing, masks and good ventilation to prevent the spread of virus
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