What is a ‘variant’? Why do we observe so many mutations in the SARS-CoV-2 virus?

What is a ‘variant’?

SARS-CoV-2 variants constitute a hot topic these days. SARS-CoV-2 virus has been producing different mutations since its first appearance. However, recently, these mutations have accumulated and are found in different subgroups in combinations and these subgroups have been defined as “variants” of the virus. In other words, the resulting mutations were clustered together in certain variants.

In virology, the term variant is used to describe a subtype of a microorganism that is genetically distinct from the main strain, but not sufficiently different to be termed a distinct strain.

There are currently 4 main variants: UK, South African, Brazilian, and Japan variants. Along with the mutations common to all of these variants, there are also separate mutations that define these different subgroups. While some of these mutations are not clinically significant, others can be escape mutations decreasing vaccine efficacy or can cause faster spreading.

Is it normal for viruses to mutate? Do all viruses mutate? Why do we observe so many mutations in the SARS-CoV-2 virus?

Virus genomes are very susceptible to mutations. Genes that are evolutionarily protected and carry vital functions for viruses are generally protected from mutations and mutation is generally less common in these gene regions. However, mutations in other regions are seen in all viruses. Especially single-stranded RNA viruses, such as SARS-CoV-2, are more susceptible to mutations since their repair mechanism in their genomes is weaker therefore mutations can be seen widely.

Do these mutations affect vaccine efficacy? What should we do to protect ourselves?

Recent findings show that especially E484K escape mutation in the SARS-CoV-2 virus can decrease vaccine efficacy significantly to less than 10% for some vaccines. This mutation was first detected in the South African variant, then in the Brazilian variant. Recently, this mutation has also been found in subtypes of some UK variants.

Due to this uncertainty about the variants, even if we are vaccinated, we must protect ourselves by wearing a face mask, keeping the social distance, avoiding crowds and indoors, and paying attention to our personal hygiene.

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