Newer variants of the coronavirus continue to pop up as reports about the emergence of new variants from many parts of the world continue to pour in. At the same time, scientists are researchers are engaged in monitoring the variants to know how many of them are more dangerous and need worrying about.
A classification system divides the variants into two main groups— variants of concern (VOC) and variants of interest (VOI). Before going into the VOCs and the VOIs however, there is some basic information to remember. All viruses undergo changes in their genetic material, called mutations. The mutations in the genetic material in the case of the coronavirus (the RNA) lead to changes in some of the proteins of the organism. Again, remember that genes (which are sequences of four letters denoting biochemical information) encode the information for producing a particular protein. In some such genes mutations lead to changes in the proteins they encode.
Most of the variants have mutations in the genes for the spike protein. The spike protein, in turn, is essential for the virus to stick to human cells and eventually infect them. Some spike protein mutations render the virus better and quicker at sticking to human cells, thus opening up the chance of greater infection rates.
Again, some mutations are thought to provide the virus with the ability to escape vaccine protection. Others cause more disease severity by escaping the immune system. Scientists and researchers are constantly monitoring the mutational impacts on the virus. Given the backdrop, the classification of VOCs and VOIs are important. However, it is to be noted that these are subjected to be upgrades with newer information constantly coming in.
Variants of Interest (VOI):
The World Health Organization (WHO) has some conditions for deciding the character of a variant. A variant of the coronavirus is denoted a VOI if it fulfills the following:
If a variant containing genetic changes which are predicted or known to affect the characteristics of the virus such as transmissibility, disease severity, immune escape, therapeutic or diagnostic escape,
If a variant is identified to cause community transmission in a significant rate or has caused multiple COVID-19 clusters in multiple countries along with an increasing prevalence, which causes increasing number of cases in time. In total, the variant has to be identified to have caused an emerging risk to global public health.
The variants listed as VOIs by the WHO are—
Eta variant: This variant has the earliest documented samples across many countries and was first detected in December 2020. The designation of Eta variant by WHO came about on March 17, 2021. This variant also has mutations in the spike protein. Till March, the Eta variant was found in 23 countries.
Kappa Variant: This variant has the earliest documented samples in India and was detected in October last year, according to the WHO. Its designation as the Kappa variant came into being on April 4, 2021.
The kappa variant has three mutations in the spike protein. These mutations have been found to provide the virus better binding with human cells, especially the ACE2 receptor (A protein on human cell which acts as the exact site of binding of the spike protein). Some of these mutations also enable the virus to evade the immune system.
Lambda Variant: The earliest documented samples of this variant were in Peru, identified in December 2020. Its designation happened on June 14, 2021.
The lambda variant has several mutations in the spike protein. By June this variant spread to 29 countries, including the US. First detected in Peru in December last year, the variant became dominant in the country by April this year with over 80% of the cases of the country linked to it.
Iota Variant: The Iota variant was documented in US samples in November 2020. Its designation came about on March 24, 2021.
This variant has over 6 mutations, all in the spike protein. The variant was found in 54 countries as of mid-June.
Variants of Concern (VOC):
According to the WHO definition a variant is designated as a ‘variant of concern’ if it fulfills the following conditions—
The variant has to meet all the points considered in a VOI.
Along with these, a variant also has to be identified to have the following aspects at a degree of global public health significance:
Increase in transmissibility or having detrimental changes in COVID-19 epidemiology, or
Increase in virulence or change in clinical disease presentation, or
Decrease in effectiveness of the currently available public health and social measures and the available diagnostics, vaccines or therapeutics.
The variants listed as VOCs by the WHO are:
Alpha Variant: The earliest documented samples of this variant were in the UK, in September, 2020. The designation came about on December 18, 2020.
The Alpha variant is well known in its substantial higher transmissibility in comparison to other variants. Some studies even reported that the Alpha variant was up to 90% more transmissible. This variant is also found to be associated to more virulence.
Beta Variant: The earliest documented samples of this variant were in South Africa – detected in May, 2020 – according to WHO. Its designation came about on December 18, 2020.
This variant has a total of eight mutations in the spike protein, three of which are of particular interest. This variant also has mutations other than those in the spike protein. This variant had been detected in 103 countries till June.
Gamma Variant: The earliest documented samples of this variant were in Brazil from November, 2020, according to the WHO with its designation coming on January 11, 2021.
This variant has 10 mutations in the spike protein. As of July 6, this variant had been found in 62 countries.
Delta Variant: This particular variant is becoming the dominant variant in many parts of the world and is also the most concerning one as of now. The earliest documented samples of this variant came from in India where it was detected in October, 2020, according to the WHO. Its designation happened on May 11 this year; it was earlier designated as a VOI on April 4, 2021.
Soon after its designation as a VOI, this variant showed a dominance over other variants wherever it was found circulating.
In total, the delta variant has 13 mutations, including the spike protein. Mutations in this variant are now linked to substantially higher transmissibility.
Till now, these are the established variants of the coronavirus included in either of the categories of VOCs or VOIs.