“BA.2” keys to the omicron sub-variant that spreads throughout the world

“BA.2” keys to the omicron sub-variant that spreads throughout the world

BA.2, dubbed “the omicron sub-variant”, made its first appearance in France a few weeks ago. First mentioned by Véran during a press conference on January 20, this new derivative of Covid-19 is currently being analyzed by scientists.

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1 Where does BA.2 come from?

Where does BA.2 come from?

BA.2 was first identified in India and South Africa in late December 2021. It is a subvariant, believed to have arisen from a mutation of Omicron (officially known as BA.1). Omicron himself was born from a mutation of Delta. Other sublineages, such as BA.3 or BB.2, have already been referenced, but have drawn less attention from epidemiologists due to the dramatic increase in cases of people who have contracted BA.2.

BA.2 has more than 20 mutations, about half of them in the spike protein. This is the famous protein that interacts with human cells and is the key for the virus to enter the body.

Is this subvariant as dangerous as Omicron?

The World Health Organization (WHO), which had classified Omicron as a “concern variant”, at this stage does not distinguish between it and its BA.2 sublineage. For his part, Véran said that “as far as we know at this time, it corresponds more or less to the characteristics that we know of Ómicron.” It’s not “a game changer” at this stage, Véran added in an attempt to reassure.

BA.2 is being studied extensively by the scientific community, but there is still no precise data on its resistance to vaccines or the severity of the Covid-19 cases it causes. Scientists are beginning to talk about it, although they remain cautious.

Virologist Tom Peacock of Imperial College London tweeted that “Very early observations from India and Denmark suggest there is no dramatic difference in severity compared to BA.1. This data should become more robust (one way or another) in the coming weeks.”

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It is necessary to have the means to detect contamination by BA.2 in the population

Peacock added that “there are likely to be minimal differences in vaccine effectiveness against BA.1 and BA.2. Personally, I’m not sure BA.2 is going to have a substantial impact on the current wave of the Omicron pandemic.

“Several countries are close to, or even beyond the peak of the BA.1 waves. I would be very surprised if BA.2 caused a second wave at this point. Even with slightly higher transmissibility, this is absolutely not a Delta-Omicron change, and instead is likely to be slower and more subtle,” he predicted.

For the epidemiologist Antoine Flahault, director of the Institute for Global Health at the University of Geneva, the monitoring of infections should make it possible to test the resistance of BA.2, in particular if people infected with the classic Omicron are again contaminated with the subvariant.

However, it is necessary to have the means to detect BA.2 contamination in the population, which seems delicate at this time and does not seem evident.

Why is BA.2 so hard to track?

BA.2 poses certain challenges to scientists as it is not easy to track. A variation in PCR testing protocols and the fact that the type of kit varies from one laboratory to another makes it difficult to reliably identify BA.2, according to Florence Débarre, a biologist at the Institute of Ecology and Environmental Sciences in Paris, interviewed by Liberation. “In the UK, the way testing is done doesn’t allow us to distinguish between BA.2 and Delta,” explains Débarre.

There is a more precise but less used tool for tracking variants: genetic sequencing of the virus. This allows the exact presence of this subvariant to be identified. But in France, for example, only some of the laboratory tests are randomly subjected to this deeper and more expensive form of analysis.

Sequencing also has the drawback of being slow, which means it is not suitable for monitoring a rapidly spreading variant.

Where does BA.2 predominate?

The subvariant has been detected in at least 43 countries on all continents. It is believed to have become the most common variant in a number of countries, including India, Denmark, and Sweden. In Denmark, the number of daily Covid-19 cases has started to rise again, just when Danes thought they had already peaked.

The UK Health Security Agency (UKHSA) identified more than 400 cases in Britain in the first 10 days of January.

“The Danish authorities do not have an explanation for this phenomenon, but it is being closely monitored,” said France’s public health agency, which follows the latest developments in Denmark. This “suggests that BA.2 is even more transmissible,” Débarre agreed. In Europe, BA.2 has also been sequenced in the UK, Germany, Belgium, Italy, and France, while North America, Asia, and Australia have also reported cases.

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