Delta variant: the two faces of its 'virulence' and what are the chances of ending up in the hospital

Irene Hartmann

08/04/2021 6:00 AM

• Clarín.com

• Society

Updated 08/04/2021 6:00 AM

A week ago an internal report from the United States Centers for Disease, Control and Prevention (CDC) leaked to the media that drew alarming conclusions about Delta's aggressiveness.

Is it proven that infection by this variant of

Covid

increases the chances of hospitalization?

In fairness to the available scientific evidence, the virulence of the Delta variant (which could soon cause another wave of Covid in Argentina) has

two

not-so-comparable

facets

.

The first "Delta aggressiveness" concerns the

social

plane

.

The second is

individual

: how aggressive the virus is once it infects us.

In these lines, an attempt will be made to clarify in what sense (and why) the pdf released from the CDC generated a forced matching of these terms.

Qualities

The great threat of Delta involves the

epidemiological

(social)

plane

.

Far from being good news, it tests (more than ever) the rusty individual commitment to avoid, at the community level, another hike in the curves.

Free vaccination against Covid train stations in the province of Buenos Aires.

Photo Juano Tesone

Is that Delta is

60% more transmissible

than the known variants of Covid, which in contagiousness equates it to chickenpox.

And not only that: the CDC confirmed that people

with a complete

vaccination schedule could contract Delta (

like any neighbor's child

) and have as

much viral load as a non-vaccinated person

.

An unsolvable game in which everyone could infect everyone.

However, even if they do get infected, those who have the full vaccination schedule will most likely avoid the severe disease, forcing people to keep an eye on just one or no doses.

So, going back to the initial question, 

are the unvaccinated more likely to end up hospitalized by Delta

, compared to the other variants of Covid?

Confidential

Although in recent days experts could be heard repeating that Delta is "worse" (citing information from the CDC as a source),

the leaked document did not confirm such aggressiveness at all

.

"It

could

be more aggressive," the confidential document outlined, and refers to a footnote containing three papers.

One of them, by Scottish experts, appeared in

The Lancet

in mid-June and was already commented on by Clarín.

It does not speak of increased virulence but rather analyzes the interaction of Delta with vaccines.

The Minister of Health, Carla Vizzotti, and the Chief of Cabinet, Santiago Cafiero, receive Covid vaccines in Ezeiza.

Photo: Presidency

Another ("

Progressive Increase in Virulence of Novel SARS-CoV-2 Variants in Ontario, Canada, from December to July, 2021

") cites the effects of Covid in a group of observed patients, classified with the flimsy label of "

probable Delta

" .

From the last one, “

Clinical and Virological Features of SARS-CoV-2 Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7, B.1.315, and B.1.617.2

”, by experts from the National Center for Infectious Diseases of Singapore, a very clear passage could be paraphrased.

They explain that Delta was associated with a greater chance of developing pneumonia, but 

the sample "was not statistically significant"

, so "it is uncertain whether the association between severe infection or pneumonia is related to an effect of this variant."

Certainties

Clarín

spoke with two "indispensable" researchers from the Institute for Biomedical Research in Retroviruses and AIDS (INBIRS):

Jorge Geffner

, an expert in immunology and Senior Researcher at Conicet, and

Jorge Quarleri

, fully dedicated to virology and Principal Investigator at Conicet.

“First of all, Delta is

tremendously more contagious

.

Second, it requires a two-dose schedule to achieve a

protective efficacy of 80% to 85%

.

There is no serious data to indicate that it is more aggressive, "Geffner said.

"Obviously 

more people will get sick

. If they are not vaccinated, more people will die because if you have more cases, consequently there will be more deaths," he said.

He also recalled that "the

viral loads

of those infected with Delta can be

between 100 and 500 times higher in the nose and mouth

compared to the P1 (Manaus), Andean and British variants".

Is it possible, then, that the CDC has launched a message seeking to achieve 

greater adherence to vaccination

of the American population?

Geffner found it reasonable.

With hospitalized for coronavirus, the corridors of the intensive therapy of Hospital Del Carmen, in Mendoza.

Photo: Ignacio Blanco / Los Andes

Quarleri agreed that “for now there is no

basic support

to affirm that Delta has greater virulence.

It is only factual, observational ”.

However, he shared a different idea of ​​the phenomenon: “With higher levels of virus in the upper respiratory tract, we might think that from there a more pronounced imbalance is promoted in the lower tract;

an

immune response that could become unbalanced

”.

Of this "imbalance", the excessive response (or cytokine storm) that the body generates trying to defend itself from the virus, there was much talk.

What follows is not a certainty but a speculation, Quarleri clarified: “In more serious conditions, a dysregulated immune response is seen, as if paralyzed.

A trigger that we know about - for other infections - appears when viral load levels are high.

They are capable of promoting a kind of

immune paralysis

”.

A good one?

Quarleri shared a very recent preprint entitled "

Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine breakthrough infections: a multi-center cohort study

", which relativizes "identical" contagiousness on the part of immunized and non-immunized.

In those vaccinated, the viral load for Delta would fall more rapidly

.

In any case, it is convenient to become mentally aware: the third wave through Delta could come, especially if it is added that only

15% of the Argentine population has two doses

, that

cultural resistance

to comply with prevention measures is almost a local pride and that the

Argentine

health

system is weak.

It could easily become "stressed" again.

Therefore, Quarleri concluded: “Given the higher viral load in the upper airways, it is especially important that, compared to Delta,

even those vaccinated with two doses do not relax the protection measures

: nose-mouth cover, distance, hand hygiene and ventilation ”.

$

Look also

Component 2 of Sputnik V in doubt: how many people would the replacement of AstraZeneca reach for

Sputnik V produced in the country: they announce that in August there will be 3 million doses of component 2