What are the BA.4 and BA.5 subvariants of Omicron?

How are these two subvariants of Omicron different from the previously reported ones (BA.1 and BA.2) that caused the third wave in India in January? Two new subvariants can lead to another wave COVID-19 In the countryside? Can previous infections and high levels of vaccination prevent serious illness and hospitalization?

India Express So far, let’s take a look at what we know about Omicron’s BA.4 and BA.5 subvariants.

How are the two new Omicron subvariants different from those that caused the third wave of Covid-19 in India?

First, the new subvariants aren’t that new. They were first identified in South Africa in January this year, but India was witnessing the third wave of Covid-19. In the next four months, BA.4 and BA.5 will become the predominant subspecies in the country, taking 55% of the other Covid-19 variants, according to the South African National Institute for Infectious Diseases. I replaced it.

Since then, two subvariants have been detected in several European countries and the United States. The European CDC has declared the two as “variant of concern” and expects that “the overall number of cases of Covid-19 will increase significantly in the coming weeks and months.”

Scientists were most concerned about the two mutations that both subvariants performed in the receptor-binding domain. It is part of a viral spike that attaches to human cells and enters the body.

According to previous laboratory studies, the F486V mutation is one of the largest escape mutations in other Omicron subvariants, meaning that the virus can evade antibodies from previous infections or vaccinations. increase.

Dr. Anurag Agarwal, Former Chief INSACOG In a tweet, the chair of the WHO Technical Advisory Group on Viral Evolution said: (The effect of the antibody is reduced). “

This, coupled with the weakened immunity of the vaccine, is likely to cause the growth of two submutants, the European CDC said.

Other previously discovered L452R mutations Delta variantIs known to increase the ability of the virus to invade human cells. Laboratory studies in China have also shown that Omicron variants with L452R mutations are more susceptible to infecting mouse lung cells. Omicron variants have serious lung effects and, unlike Delta, which leads to higher hospitalization, oxygen needs, and death, primarily affected the upper respiratory tract, so less in most places, including India. Caused a non-serious illness.

Can the two subvariants cause hospitalization, which is a more serious illness?

Fortunately, however, on the ground, BA.4 and BA.5 do not appear to have caused an increase in hospitalizations and deaths in South Africa. “The wave of infections in SA has so far peaked with low hospitalizations and deaths,” said Tuliode Oliveria, director of the South African Epidemic Response and Innovation Center, in a tweet. He is also a member of the WHO group, which is tracking the evolution of Covid-19. “Interestingly, so far, BA.4 and BA.5 seem to be slowly increasing in countries with large BA.2 waves.”

BA.2 was the dominant subvariant in India during the third wave. In fact, analysis of the global database of Covid-19 genomic sequences shows that BA.2 accounted for 62% of sequences from India in the last two months.

“Currently, the severity of BA.4 / BA.5 shows no signs of change compared to the previous Omicron strain,” the European CDC said.

Dr. Sudhanshu Vrati, current director of the Indian Genome Sequencing Consortium INSA COG, agreed.

So can the variant cause another surge in the case of India?

Dr. Vrati said: The first concern was due to the L452 mutation found in the delta mutant. However, so far, there has been no correlation between these and the increased severity of illness, hospitalization or death. And that is likely to be the case in India as well. “

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Regarding the increase in the number of cases, he states, as seen when the January Omicron variant drive wave surged cases but hospitalizations did not increase proportionately. Subvariants are unlikely to cause havoc. For increased cases, it was found that the virus always finds weak immunity, even with the standard Omicron variant of Delhi-NCR. “

He added that people didn’t have to worry, but genomic sequencing needs to keep an eye on new mutants that can lead to more cases or serious illness.