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Delta variant: how they discovered the two cases of Monserrat without nexus and why there may be others undetected


These are two people who did not travel abroad or have contact with someone who would have done so. They claim that 'there is no community circulation'.

Maria Bethlehem Etchenique

08/03/2021 17:27

  • Clarí

  • Cities

Updated 08/03/2021 17:27

There are 89 people infected with the Delta variant of the coronavirus. Seventy correspond to men and women who returned from abroad and 17 to individuals who had contact with those who had traveled.

But two, of the 89 cases registered in the country, did not leave Argentina or were linked to someone who had done so.

The link is currently unknown: it is not yet known how and when they acquired this variant, the most contagious that has been detected until today in the world.

The warning came from the virology laboratory of the Ricardo Gutiérrez Children's Hospital.

The two people, a minor and an adult - gender did not transcend - 32 years old, had gone to the Recoleta medical center, where they were swabbed and received the diagnosis.

The girl began with symptoms on July 20 and the adult or adult, on July 2, according to an official from the City's Health area to



The finding of the variant in the Children's Hospital was no accident.


is the central node of the inter-institutional Consortium for genome sequencing

and genomic studies of SARS-COV-2 (or PAIS Project).

Ricardo Gutiérrez Children's Hospital.

In the virology laboratory, Covid samples from the hospital and from other parts of the City, the Province and the rest of the country are sequenced to

know the genetic evolution of the coronavirus and monitor

which variants circulate.

Not all Covid cases are analyzed, but a proportion.

"Nowhere in the world is it possible to sequence all the cases that are detected. What is done is to define statistically representative random samples. Molecular epidemiology has historically worked like this", explains Mariana Viegas, biochemist, virologist at Gutiérrez and leader of the PAIS Project .

Since December, in the hospital laboratory


between 5% and 10% of the Covid diagnoses

of the previous week

have been sequenced


"This time," Viegas adds, "it was 10% and in that context the Delta variant was found."

The selection of the sample is based on different variables: that the cases are positive,

that they do not have a history of travel abroad or a connection with a traveler,

that they are not related to each other (study the members of a family who were contagious each other). one would not be representative) and that they have a determined viral load (TC <30).

If two people infected with Delta were found on a 10% analyzed,

it can be inferred that the real figure for this variant is much higher

, if you think about it in scale.

In order to capture undetected cases, in recent days door-to-door searches were carried out in houses and shops in Monserrat, within a radius of four blocks from the girl's home.

For the two positive cases of Delta in Montserrat, they carried out a detection operation in four surrounding blocks and isolated 41 people.

Photo Emmanuel Fernández

So far there are

41 isolated people,

who were tested preventively.

Two have Covid, but the health authorities deny that they have the Delta variant, as they are not close contacts of the girl and her family.

Regarding the adult or adult with Delta, no other positives were established and the investigation, according to Health sources confirmed to


, was closed,

without the contagion being able to be clearly reconstructed


The Delta variant was first identified in India in October 2020. Seven months later, the World Health Organization designated it as a variant of concern.

Today it is present in

at least 132 countries


Compared to the original virus, which emerged from Wuhan, it is more contagious and effective in its ability to infect.

Preliminary studies show that it is 60% more transmissible than the Alpha variant (detected in the UK), which was already 65% ​​more transmissible than the original coronavirus.

The predominant variant

Today, in the Metropolitan Area, the trend shows a

greater presence of the Gamma variant

, detected in Brazil;

followed by the damba, also called Andean;

and then the Alpha in a smaller proportion.

The path of penetration of each variant is similar to the beginning of the pandemic, in March 2020, when the country first observed cases imported from abroad (people who were infected outside the country and who were diagnosed in Argentina), then close contacts of these cases, then cluster transmission and, finally, community transmission.

The concept of

community transmission means that an epidemiological outbreak became so relevant that it is already circulating in the population

, among a high number of people who cannot identify the origin of their infection.

For Mariana Viegas, it is still not correct to speak of community transmission at the local level, although she

does not rule out that this stage will be reached very soon


"You do not have to stop at what happens in a week, but observe the progression. For now, two cases of the Delta variant have been detected without epidemiological nexus, but that does not mean that there is community circulation.

This will happen when the detection is systematic

and sustained

over the weeks. "


Look also

"Antibodies to full": what is known about the contagion after the vaccine

They confirmed 89 cases of the Delta variant: the detail of infections in each province

When to be tested for Covid, what methods are there and which is the most effective

Source: clarin

All news articles on 2021-08-03

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