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The dangerous Delta variant: experts explain how long the Covid will continue to mutate


The appearance of the Indian variant raised the alarm globally. While 'herd immunity' is still a utopia in Argentina, what is the horizon against the threat.

Rocio Magnani

06/19/2021 6:00 AM

  • Clarí

  • Society

Updated 06/19/2021 6:00 AM

The concept of "herd immunity" seems to have been far behind in 2020, but that is where all global efforts were directed.

At the beginning of the



, it was estimated that with 60 or 70 percent of the population with antibodies to SARS-CoV-2 - acquired by natural infections or by vaccines - a

collective armor

would be achieved

that would prevent circulation almost by full.

The "intelligence" of the new coronavirus or its speed to mutate, in

contrast to the rate of vaccination in the world

, is one of the main reasons that make this idea falter.

In just one year, four variants

of concern


and another 6, classified by the WHO as

“of interest”


Delta was the last to join the first group and it has already been proven that it has a

certain evasion

of the immune response generated by vaccines.

Among the most paradigmatic examples, it is responsible for a

significant increase

in cases in the United Kingdom, despite the fact that in the country

three out of four adults

have at least one dose of vaccine.

According to official reports, more than 90 percent of those currently infected in that country were infected with the Delta. Originally detected in India, the variant is

60% more contagious than Alpha

, which was first studied in the British city of Kent, and is 1.8 percent more likely to lead to hospitalization. In addition, the different vaccine formulas

decrease their effectiveness

with respect to this variable.

It is not a return to the starting point

, when vaccines did not exist.

Although the 8,210 new infections reported on average each day in the United Kingdom mean that

infections quadrupled

in just over a month, the figure only represents


in relation to the maximum peak of infections registered at the beginning of January.

It remains to be seen how the government of Boris Johnson will contain this rise in cases.

The vaccination rate grew in recent days.

Photo: Ministry of Health

For the virologist Jorge Quarleri, biochemist at the UBA and main researcher at Conicet, the new variant - which according to official reports still does not circulate in Argentina - is a sign that

relaxation will have to wait

, in addition to the fact that policies that look only at borders inside they are insufficient. "The Delta is definitely posing a challenge to us that will surely force us to think about whether it is necessary to

update the vaccine

against Covid-19," he defines.

Laboratory studies, carried out with hamsters, show that this variant "multiplies with

a substantially greater efficiency

compared to previous variants", he explains and graphs with a war metaphor: it has more opportunities to win both for "quantity of soldiers", because the variant "plants in the respiratory tree a

higher quantity of virus than

other variants", and for its




In his words: "The soldiers of the Delta seem to have a sufficiently sophisticated cosmetic surgery so that the antibodies generated by the vaccines, when they see the face of their opponent,

fail to recognize him

exactly in all his parts."

Bordering the middle of the second year of Covid-19, there is

more uncertainty than certainty

about when it will be possible to achieve a containment of the coronavirus as a pandemic, although slowing down the circulation becomes a priority to make it a controllable threat.

It is not just about advancing vaccination.

"As long as we have hyper-populated countries in which hygienic and sanitary conditions do not allow for a level of coverage such that the virus does not continue to find hosts in which to replicate and

will continue to generate variants,

" he said.

Variants in Argentina

The frequency with which the new variants of Covid-19 appear, "with these levels of circulation in the world

is something to be expected and normal

in the biology of viruses,"

the national director of Epidemiology, Analía Rearte,

explained to


the flu, which varies every year, the viruses

continually have mutations and changes

. That's normal. What happens is that when these changes affect some proteins that are related to the transmissibility or the severity of the disease they cause, problems start to be generated ”, he continued.

In Argentina,

two cases of the Delta variable

were detected at the end of April

, which were contained in the Ezeiza airport and did not lead to major complications.

As public officials and specialists affirm, it is essential to

delay its community circulation for as

long as possible.

The variants that circulate the most are Gamma (Manaus –variant of concern to WHO), Lambda (Andean, of “interest” according to WHO) and Alpha (British, also of concern).

Tests in a square of the City, another weapon to isolate and stop the circulation of the variants.

Photo: EFE

“With these variants and these vaccines that we have today (Sputnik-V and Astrazeneca, mainly), both in one and two doses, the effectiveness is very good.

What is going to happen later?

I do not know. We hope that they can continue to be effective against all the other variants ”, the official wished, and clarified that, in any case,“ the most difficult part which was to generate the vaccines for SarsCov2, we already passed it, because it is not the same to have to develop a vaccine from scratch to have to

adjust or accommodate

a vaccine to a certain different variant ".

The National Administration of Laboratories and Health Institutes (Anlis) "Dr. Carlos G. Malbrán" is the national body of reference, a role that it already had in 2009 with Influenza A and that it has every year in seasonal outbreaks, such as the of flu.

Josefina Campos, coordinating biochemist of the ANLIS Malbrán Genomic Platform, leads the team that has been

monitoring the coronavirus

since the arrival of the pandemic. “The virus evolves and changes and mutates and generates new variants if the virus circulates. As long as we can

somehow cut off the circulation of the virus

, with all the behaviors that we all already know and vaccination, it helps. But regarding the evolution of the virus, if the vaccine appearance influences this or not, we will not know until we see later how the virus is responding ”, he analyzed.

The Russian laboratory Gamaleya reported this week that it will work on offering a

vaccine booster

for other brands to deal with the Delta variant.


asked Campos if he considers that an evolution of Covid-19 similar to that of the Flu could be considered with interannual vaccines that respond to the new strains?

"Not to compare it with the flu, because they are different types of virus and have different behaviors, but the fact that an

annual vaccination or an annual reinforcement

is done is something that we still cannot determine well," he considered.

“RNA viruses, such as Covid-19, when they reproduce, in that need to generate many viral particles, they

make mistakes


Some of these changes in the genome, which we call mutations, continue over time and generate variants.

This virus is an RNA virus that particularly has a system by which it

corrects these errors

, with which it even has a lower mutation rate than others, such as HIV for example, "he pointed out.


Look also

Chile: they fail to stop the coronavirus and analyze applying a third dose of the vaccine

COVID: Chinese infectologists say another pandemic may come

Source: clarin

All life articles on 2021-06-23

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