Omicron BA.4 is here: What is the sub-variant and can it cause another COVID-19 wave?

India has reported the first case of Omicron BA.4 sub-variant in Hyderabad. First detected in South Africa, it is highly transmissible. While Indian experts believe COVID-19 cases may rise, it is unlikely hospitalisations will

FP Explainers May 20, 2022 10:46:27 IST
Omicron BA.4 is here: What is the sub-variant and can it cause another COVID-19 wave?

The first case of Omicron subvariant BA.4 was detected in Hyderabad. AFP

The first case of the Omicron BA.4 variant in India has been reported from Hyderabad through India’s COVID-19 genomic surveillance programme on Thursday.

According to scientists associated with the Indian SARS-CoV-2 Consortium on Genomics (INSACOG) said that from India, details of a BA.4 sub-variant were entered on GISAID, a global science initiative that provides open access to genomic data of influenza viruses and the coronavirus responsible for the COVID-19 pandemic, on 9 May, reported Moneycontrol.

Random cases of BA.4 may have also been detected in other cities in India over the last few days, said a scientist with the Indian Council.

What is the BA.4 variant?

The BA.4 is a sub-variant of Omicron and has been declared a variant of concern along with BA.5 by the European Centre for Disease Control and Prevention.

In early May, the World Health Organisation (WHO) that sublineages, BA.4 and BA.5, of the highly transmissible Omicron variant, first detected in South Africa “have acquired a few additional mutations that may impact their characteristics”.

Where was the BA.4 variant detected?

The BA.4 sub-variant was first detected in South Africa in January.

The earliest BA.4 sample was collected in South Africa on 10 January but data shows that the “accumulation of genomes” and geographic spread of the subvariant is more recent, according to a recent report by United Kingdom’s Health Security Agency.

Since then, it has become the dominant variant in the country along with BA.5. Together they have replaced 55 per cent of the other Covid-19 variants, according to the National Institute of Communicable Disease-South Africa.

Which other countries have they spread to?

The sub-variants are circulating in several European nations and the United States. BA.4 and BA.5 have been detected in Botswana, Germany and Denmark, among other countries, WHO’s technical lead on COVID-19 Maria Van Kerkhove said Thursday.

BA.4 and BA.5 are spreading more rapidly in some countries than previous Omircon variants, specifically BA.1 and BA.2.

At least 16 countries have reported about 700 cases of BA.4, reports CNBC.

Omicron BA4 is here What is the subvariant and can it cause another COVID19 wave

The earliest BA.4 sample was collected in South Africa on 10 January. AFP

How deadly are the sub-variants?

The BA.4 and BA.5 sublineages appear to be more infectious than the earlier BA.2 lineage, which itself was more infectious than the original Omicron variant, Tulio de Oliveira, director of the Centre for Epidemic Response and Innovation, South Africa, told Bloomberg. He is also a member of the WHO group tracking the evolution of COVID-19.

The mutations in the lineages “allow the virus to evade immunity”.

“We expect that it can cause reinfections and it can break through some vaccines because that’s the only way something can grow in South Africa where we estimate that more than 90 per cent of the population has a level of immune protection,” he added.

“Wave of infections in SA has peaked with, so far, low hospitalisations and deaths,” de Oliveria wrote in a tweet. “Interesting that, so far, in countries with a large BA.2 wave, the BA.4 and BA.5 seem to be increasing slowly.”

Meanwhile, the scientists in the United States studying BA.4 and BA.5 have said that so far, the key difference between the newer versions of Omicron and the one that previously spread through the country is transmissibility. White House’s chief medical adviser, Dr Anthony Fauci, has estimated that the sub-variants are 50 per cent more transmissible than the original Omicron lineage.

Both sub-variants have additional mutations in the spike region, a part of the virus that is used to invade human cells, and unique mutations outside of that region, according to a WHO report published Wednesday. Such mutations are associated with “potential immune escape characteristics,” the report said, according to CNBC.

Omicron BA4 is here What is the subvariant and can it cause another COVID19 wave

According to scientists in India, BA.4 does not pose a major threat to the country. AFP

What are scientists in India saying?

Experts in India believe that a new surge is likely to stay at low levels given the extensive immunity in the Indian population because of the Omicron wave that hit India in January.

“We expect a similar kind of low surge in the coming days but is highly unlikely that there will be any dramatic rise in hospitalisation due to severe COVID-19 sickness,” said an official attached to the National Centre for Disease Control under the Union health ministry which is heading the INSACOG project, reports News18.com.

According to Dr Anurag Agrawal, dean of biosciences and health research at Ashoka University, at antigen level, BA.4 and BA.5 are similar to BA.2 but have substantial differences compared to BA.1. “I expect the risk of large BA.4 and BA.5 outbreaks to be low in regions such as India, where BA.2 caused large waves.”

Virologist Dr Gangadeep Kang told The Times of India that metrics matter in assessing risk to health systems. “In assessing the occurrence of a wave, the metric is: (1) how transmissible is the variant and (2) what proportion of the population has been vaccinated or infected?”

“Based on India’s experience with BA.2, I do not anticipate any health system stress from BA.4 and BA.5. As for increase in cases that is certainly feasible but not guaranteed,” she said.

With inputs from agencies

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