Why is the Indian variant a variant of concern?

Variants of covid-19: what worries science the most 0:49

(CNN Spanish) – The variant of the new coronavirus first detected in India is of “concern,” the World Health Organization said earlier this week. What does that mean and what impact does that designation have for the pandemic? Dr. Huerta explains to us.

You can listen to this episode on Spotify or your favorite podcast platform or read the transcript below.

Hello, I am Dr. Elmer Huerta and this is your daily dose of information about the coronavirus. Information that we hope will be useful to take care of your health and that of your family.

The World Health Organization has decided to classify variant B.1.617, discovered in India – which, incidentally, has just been discovered in Argentina – as a variant of concern. So today we will see what a “variant of concern” means.

What is a variant?

First, let’s remember what a variant is.

As we heard in the March 31 episode, it is accepted that the new coronavirus originated in China, in an area near the city of Wuhan, and that from there it spread to other parts of the world.

Let us also remember that every time the virus infects a person, it has the possibility of mutating, that is, of changing its genetic makeup. For this reason, the more infections that occur in a region, the greater the possibility that – as we saw in the episode of January 5 – variants of the virus could originate, that is, new mutant versions of the virus.

That said, by progressively spreading from its origin in Wuhan and causing millions of infections in neighboring countries, the virus progressively changed in its molecular structure that – thanks to genetic sequencing – can be analyzed in detail.

And that was the enormous contribution of a group of German and British scientists, analyzing the genome of the virus since its appearance and determining its evolution through the mutations that occurred as it progressively spread to neighboring countries.

The phylogenetics of the new coronavirus

This is what is called a study of phylogenetics (phylo means clan or tribe, and genetics means origin).

Studying the phylogenetics of the new coronavirus then allows us to analyze the genetic changes that, as if it were a fingerprint, occurred while it spread throughout the world, and could help classify them.

In a study published in the journal Proceedings of the National Academy of Sciences in the United States, on April 28, 2020, the researchers report the result of the analysis of the first 160 genomes of the virus isolated from humans in several countries between April 24. December 2019 and March 4, 2020.

Their studies made it possible to classify the new coronavirus, according to its evolution, into three groups or genetic trunks, A, B and C.

Type A genetic stem

Type A is the closest virus to that discovered in bats and is considered the original genome of the new human coronavirus. That variety was already present in Wuhan, but surprisingly it was not the predominant type of virus in the city during the beginning of the pandemic.

Mutated versions of this A virus were found in Americans who lived in Wuhan and in patients in the United States and Australia.

Type B genetic stem

Type B – different from type A only by two mutations – was the main type of virus in the city of Wuhan and very common in patients from East Asia.

However, phylogenetic analysis showed that this variant did not travel much beyond East Asia. A poorly understood phenomenon of adaptation to that geographic area or resistance to its spread in other countries.

Type C genetic stem

For its part, variant C – derived from variant B – is the main European type of the new coronavirus. It was found in the first patients in France, Italy, Sweden and England.

It is not found in patients from mainland China, but it is found in those in Singapore, Hong Kong, and South Korea.

We must clarify that the letters that appear in front of the variants, for example B.1.117, B.1.351 or C.37 do not come from the virus lineages discovered in the study, but from a complicated classification system for SARS-CoV2 called PANGO, which, starting from the original virus in Wuhan, is putting letters and numbers to the viruses that are being described by genomic analysis in the world.

Variant of Interest and Variant of Concern: What the CDC Says

Regarding variant types, the U.S. Centers for Disease Control and Prevention (CDC) classifies variants into three types: variants of interest, variants of concern, and high consequence variants. .

Some characteristics of a variant of interest include – and we quote the CDC – specific genetic markers that predict that it may affect transmission, diagnosis, therapy, or response to neutralizing antibodies to the virus.

Variants of interest may require public health actions, including virus surveillance, or epidemiological investigations to assess the ease of transmission, whether they cause more serious disease, response to treatments, and whether current vaccines offer protection.

Some examples of variants of interest are B.1.526, from New York, and P.2, from Brazil. Variant B.1.617, from India, was in this group of interest, but has now been reclassified to the next group, variant of concern.

On the other hand, the variants of concern are those – and we quote the CDC – in which there is evidence of a greater contagion capacity, which produce a more severe disease (for example, an increase in hospitalizations or deaths), a significant reduction in the neutralization by antibodies generated during a natural infection or previous vaccination, a reduced effectiveness of treatments or vaccines and false negatives in diagnostic detection tests.

Variations of concern may require appropriate public health actions such as notification to WHO under the International Health Regulations, notification to CDC, local or regional efforts to control the spread, and development of new vaccines or diagnostic tests.

Finally, happily, there is no high consequence variant so far.

Do you have questions about the coronavirus?

Send me your questions on Twitter, we will try to answer them in our next episodes. You can find me at @DrHuerta.

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And for the most up-to-date information you can always head to Thanks for your attention.

If you have any questions you can send them to Dr. Elmer Huerta through Twitter. You can also head over to for all episodes of our “Coronavirus: Reality vs. Reality” podcast. fiction”.

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