What are various variants of SARS- CoV-2 (COVID-19) detected so far?

The SARS- CoV-2, the coronavirus that causes COVID-19 has mutations and led to multiple variants. Many variants of the virus are found in different parts of the world. Some of these are popularly known as UK variant, South African variant, etc. A new double mutant variant has recently been discovered in India. Here is a review of all these variations.

The total confirmed cases of COVID-19 have crossed 142 million and over 3 million deaths were reported worldwide, as of 20 April 2021. India recently surpassed Brazil as the country with the second highest number of cases reported. confirmed in the world. , after USA. India has so far reported more than 15.6 million cases and 1.82 lakh deaths. Since 16 April 2021, India has been reporting more than 2 lakh new cases daily. States have begun installing local curfews and locks to curb the rapid spread during the current wave. India’s surge in outbreaks has alarmed the discovery of new variants of the virus. The rapid spread during the current wave means that countries such as the UK have included India in the red list of countries where travel to the UK has been banned for non-UK residents or Ireland or a British citizen if they have been in India in the previous 10 days.

Over time, variants of the virus emerge through mutations

Viruses are constantly changing. Genetic variants occur with time leading to the emergence of new variants with variable traits. SARS- CoV-2, the coronavirus behind the ongoing pandemic, is no exception. Each coronavirus contains a sequence of approximately 30,000 RNA letters. When the virus infects a living cell, it copies itself and in doing so, there may be small copying errors called mutations that lead to a new ‘lineage’ of the virus as the virus mutation passed down. A variation is a virus with one or more new mutations compared to the original virus. That is, with the mutations, the variant virus is genetically distinct from the main strain but not different enough to be considered a new strain.

CDC has classified variants into 3 broad categories

It has been more than a year since the pandemic began. Multiple variants of SARS- CoV-2 are found globally. The Centers for Disease Control and Prevention (CDC), USA has classified all the variants into three Variations of Interest (VoI), Variants of Anxiety (VoC), and High Outcome Variants (VoHC).

VoI and VoC have a D614G mutation that increases virus transmission

Those variants that show an increase in transmissibility, are more infectious and cause more serious disease leading to more hospitalizations or deaths, less response to treatments and vaccines, a significant reduction in neutralization by antibodies produced during infection or vaccination previous failure, or failure in diagnostic detection. treated as Anxiety Variants, VOC. Currently, there are five VOCs according to CDC. All five variants share one specific mutation called D614G which makes the virus more transmissible than its original form.

There are 3 variations categorized as Variations of Interest (VoI)

Variants with specific genetic markers that have been associated with changes in receptor binding, reduced neutralization by antibodies produced against previous infection or vaccination, reduced treatment efficacy, potential diagnostic effect, or predicted increase in transmissibility or severity disease in VOIs. That is, the mutations may help the virus avoid antibodies and treatment but it is not as infectious as VOCs. CDC has classified three variants as VOIs. All three, share a specific mutation, D614G, and have the potential to avoid antibodies.

VoHCs are variants with evidence that preventive or medical countermeasures have significantly reduced effectiveness compared to other variants. To date, no SARS-CoV-2 variant falls under this category.

INSACOG found variations in the UK and South Africa in India in March 2021

The Indian SARS-CoV-2 Genomics Consortium (INSACOG) is a network of ten laboratories set up in December 2020 for monitoring SARS-CoV-2 genomic changes in India. INSACOG has detected 771 VoC in a total of 10787 positive samples shared by States since its inception. These include 736 samples positive for the UK lineage viruses (B.1.1.7). 34 samples were found positive for South African dynasty viruses (B.1.351). One sample was found to be positive for Brazilian (P.1) viruses, spread across 18 states in March 2021.

A new variant with two mutations was discovered by INSACOG in India

INSACOG also discovered the double mutant variant in India when analyzing samples from Maharashtra which revealed an increase in the fraction of samples with E484Q and L452R mutations. The E484Q mutation is similar to that found in the B.1.1.7 dynasty identified in UK and B.1.351 variants identified in South Africa which gives the virus the ability to evade antibodies and the L452R mutation is like the one in the California B.1.427. and variants B.1.429, which are infectious. Both mutants are present in the B.1.617 variant of SARS-CoV-2 found in India. Research about the virus is ongoing, and the CDC has not yet classified this virus.

B.1.617 has spread to the USA, UK and other countries

The new double mutant has spread to the USA, Germany, the UK, Australia and Germany. It has also been found in Belgium, Ireland, Namibia and New Zealand. The higher transferability of this variant has not yet been established, according to a recent Ministry of Health press release. He also added that RT PCR tests used in India do not miss these mutations and that the sensitivity and specificity of the RTPCR assays remain the same as earlier.

Sequences of the B.1.618 lineage were found in West Bengal

Initial sequences in B.1.618 dynasty have been identified in West Bengal, according to a tweet from Vinod Scaria, a researcher at the Scientific and Industrial Research Council (CSIR-IGIB) Institute of Genomic and Integrative Biology. Members in this dynasty were also reported from the USA, Germany, Switzerland and Singapore. However, it is mainly found in India. The variation is characterized by the deletion of two amino acids in the spike protein —H146del and Y145del, both of which are associated with immune escape or in other words bypass antibodies. In addition, the variant also carries the D614G mutation in the spike protein and the E484K mutations, which are associated with increased infectivity and immune escape, respectively. It was also observed that the proportion of SARS-CoV-2 samples of the B.1.618 lineage has been increasing in West Bengal in recent months. However, there is no definitive data as yet to find out that the new dynasty was driving the epidemic in West Bengal.

The efficacy of the vaccine may be reduced but may not be completely ineffective according to WHO

In identifying new variants, a major concern is the effectiveness of vaccines given worldwide. As seen before, the effectiveness of the AstraZeneca vaccine against the B.1.351 variant of South Africa was low. Studies also suggest that the effectiveness of the Pfizer-BioNTech vaccine and the Moderna vaccine has been significantly reduced in the presence of the E484K mutation. The ICMR study claims to have discovered that Covaxin is effective against multiple variants of the coronavirus including the originations in the UK, Brazil and South Africa. The vaccine has also been reported to be effective against the double mutant strain. But detailed information and information on vaccine efficacy against emerging variants is still not available. However, the vaccines being developed and approved are expected to provide some form of protection against the new variants. Alterations or mutations in the virus do not need to make vaccines completely ineffective, according to WHO. Furthermore, since the mutations and variants are related to the original strain, the changing composition of vaccines can also help if they prove to be less effective.

Taking precautions is essential

With the increasing number of mutations and variants being discovered worldwide, emphasis must be placed on using public health interventions to slow the spread of viruses which can also slow the emergence of variants as more mutations and variants are formed through infections. For this, the precautions of respiratory hygiene, social isolation, wearing masks, and vaccination must be followed.

Advice to the public
Source: WHO