It has been almost two years since the highly contagious Covid-19 first came to the emergence and literally wreaked havoc throughout the world. With passing time, several variants of the original virus in the form of Alpha, Beta, Gamma, Delta, Mu, Epsilon, Theta, Zeta, and Omicron and their respective sub-variants have undoubtedly imposed major damage on people across the globe.
World Health Organization (WHO) has already confirmed Omicron, the B.1.1.529 lineage of SARS-CoV-2 as a Variant of Concern (VOC), in late November 2021. During this designation, Omicron mainly comprised three sister lineages, which are BA.1, BA.2, and BA.3, each differing from the other in terms of mutation. Although the variant BA.3 remained relatively rare, the other two became sole contributors to yet another upsurge in Covid-19 cases globally, with BA.2 becoming the predominant one. They even led to vaccine breakthrough infections (infection in fully vaccinated people) in most countries.
Earlier this year, in April 2022, researchers from South Africa first identified two more sister lineages of the Omicron variant via their genome sequencing efforts which were later designated as BA. 4 and BA.5 by the Phylogenetic Assignment of Named Global Outbreak (PANGO) network. Although the positivity rate of Omicron cases was gradually coming down in South Africa and the rest of the world, the latest variants led to an upsurge in Covid cases not only in South Africa but also in other countries, slowly emerging as the dominant variants and replacing the other variants of Covid-19.
Here’s all you need to know about the BA.4 and BA.5 sub-lineage of the Omicron variant:
How Does The BA.4 and BA.5 Differ From The Original Omicron Sister Variants?
Several types of research on the latest variants confirm that the sub-variants BA.4 and BA.5 have a huge growth advantage over both BA.1 and BA.2, either owing to their ability to transmit faster from one person to another or their proficiency to escape vaccination acquired immunity.
Although BA.4 and BA.5 are quite distinct from both BA.1 and BA.2, they share an identical spike protein and differ chiefly from the original lineage by three mutations and one deletion. That being said, these mutations also have a lot of common traits with the BA.2 variant, one of the dominant Variants Of Concern throughout the world. Out of the three distinct mutations found in BA.4 and BA.5, one of the mutations found in each of their spike proteins is L452R, which is believed to be responsible for the high infection rate of both BA.4 and BA.5.
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What Is The L452R Mutation?
The L452R mutation is defined as the change in the genome code at the position L452R. This mutation was also seen earlier in Delta, Kappa, and Epsilon and is known to enhance the virus’ ability to enter the human cells. These mutations have already been affirmed as responsible for faster infectivity and transmission rate and the ability to escape neutrality by monoclonal antibodies. Preliminary research even suggests that the BA.4 and BA.5 lineages may even be competent enough to bypass the immunity gained by the previous BA.1 lineage causing breakthrough infections.
Does The BA.4 and BA.5 Variants Pose A Threat In India?
The existence of the BA.4 and BA.5 sub-variants was first ascertained in India by the INSACOG (Indian SARS-CoV-2 Genomics Consortium) on May 22, with cases in Tamil Nadu and Telangana coming to the surface. The cases were first detected in two patients from Telangana and Tamil Nadu, respectively. While one of the patients who tested positive was a 19-year-old woman from Tamil Nadu, the other one was an 80-year-old man from Telangana. Both the patients were fully vaccinated, had no travel history, and only showed mild clinical symptoms.
According to WHO, another mutation in the spike proteins of both the sub-variants, namely F486V mutation, is detected as one of the biggest escape mutations for other Omicron sub-variants, which signifies that it makes the BA.4 and BA.5 lineages better able to evade the antibodies from previous infection or vaccination. Due to this ability of the BA.4 and BA.5 sub-variants, on May 12, the European Centre for Disease Prevention and Control (ECDC) classified the BA.4 and BA.5 Omicron lineages of the Covid-19 again as Variants Of Concern (VOC), upping it from being Variants Of Interest (VOI).
Dr. Rajeev Jayadevan, a well-known epidemiologist and co-chairman of the Indian Medical Association (IMA), says, since the BA.4 and BA.5 sub-lineages are quite similar to the previous mutations of the Omicron, the chances of another massive wave of infection in India is the bare minimum. This is chiefly due to the high levels of hybrid immunity achieved and about 90 percent of overall vaccination coverage, which is much more than that of South Africa.
Additionally, since we already have the experience with the BA.4 and BA.5 sub-variants from other countries, it can be considered that there has been no correlation between these variants with increased infection severity, hospitalization, or fatality rate.
With the current data in hand, for the time being, it can be concluded that there is no need to panic, but researchers must continue genomic sequencing to detect more new variants that might still be a cause of concern. However, one must also follow safety protocols and precautionary measures to stop the spread of infection altogether.