Why Delta is concerned, the variant of the coronavirus that will be dominant in the world

Over the past month and a half, a new shadow began to cover the pandemic sky that appeared to be starting to clear. Nail new variant of original SARS-CoV-2 coronavirus, this time described in the India, that he was going through a humanitarian tragedy which is only now beginning to subside. In India, daily confirmed cases of Covid-19 They reached 414,188 on May 6, and deaths reported at 7,374 on June 10, hospitals could not cope, people died at the gates of institutions, in some crematoria structures melted down. have lit the ovens. Horror on Earth, live and live, without the need of any dystopia transmitted by digital platforms.

In this scenario, a variant has started camping: the line B.1.617, which had already been detected in this Asian country in December 2020. From there, a highlighted, originally known as B.1.617.2, who was now baptized by the World Health Organization (WHO) as Delta, after giving the worrisome variants (VOC, Variants of Concern) matching names with the letters of the Greek alphabet, to avoid associations with the countries where they were first detected.

So far it is believed that Delta is the most transmissible variant of the. The United Nations health agency said it continued to see “significantly higher transmissibility” and a “growing number of countries reporting epidemics associated with this variant.” Even countries with high immunization rates experience a increase in cases In recent weeks, “so no one is out of danger,” warned Mike Ryan, executive director of the WHO’s health emergency program, on June 2.

Delta is present in at least 74 countries of all continents and is the 91% of new cases of Covid-19 reported in the UK. Currently, around 10% of confirmed patients in the United States are due to the Delta variant, and that ratio doubles every two weeks, according to Scott Gottlieb, former commissioner of the Food and drug administration (FDA). A study by the Indian government found that Delta has become by far the most dominant strain in this country. China’s Guangdong province has closed areas in an attempt to control an outbreak of cases largely due to the Delta variant.

In the Argentina, the variant would not yet have community circulation. According to Mariana Viegas, researcher at the virology laboratory of Ricardo Gutiérrez Children’s Hospital, Delta was detected on April 24 in two Argentinian miners in France. Until the close of this edition, no new cases have been found by the Inter-institutional consortium for genome sequencing and genomic studies of SARS-CoV-2 (PAIS project), which integrates. And it is essential that the variant does not enter, by travelers, to the point of becoming communal.

Why is this worried

WHO classifies a variant as a VOC when it is associated with an increase in transmissibility or a detrimental change in the epidemiology of Covid-19; increased virulence; or a decrease in the effectiveness of public health measures or available diagnostics, vaccines or therapies.

What the features make the delta variant a concern? The different variants of the original pandemic coronavirus are characterized by mutations or alterations in the genetic material of the virus. An RNA virus, like SARS-CoV-2, is made up of about 30,000 base pairs of amino acids, arranged like building blocks next to each other. An alteration of one of these bases causes a mutation, thus changing the shape and behavior of the virus. And although viruses are constantly mutating, the variant Delta contains several mutations in the Spike protein (or pic). At least four of these mutations are important for the consequences they entail.

One of them, the L452R, first reported in Denmark by March of last year, it is more transmissible and is associated with reduced effectiveness of antibodies and the ability of vaccines to neutralize the virus.

Another mutation, the P681R, has been associated with chemical processes that may improve the transmissibility of the virus. The mutation D614G, for its part, was first documented in the United States: according to the Centers for Disaster Control and Prevention (CDC), “there is evidence that variants with this mutation spread faster”. And finally, the fourth risky mutation of Delta is the T478K, associated with increased infectivity.

After several scientific studies, it is now estimated that Delta is up to 60% more transmissible than Alpha (which we knew until recently as the British variant or B.1.1.17), which itself is more transmissible. than the original strain of the Alpha strain. coronavirus detected in China in late 2019, and that’s why scientists believe it has become a dominant variant globally. In the week of May 27 to June 9 alone, admissions of people with Covid-19 to UK healthcare facilities increased between 51% and 64%.

On the other hand, preliminary evidence shows that Delta is associated with at least twice the risk of being hospitalized por Covid-19 between who are not vaccinated, according to a Scottish study published in the specialist journal The Lancet.

Something that has also been observed is that the ages of those most affected have been reversed. In the case of the United Kingdom, more than 70% of hospital admissions correspond to patients under the age of 65, whereas in January of this year (when vaccination had already taken a little over a month to develop ), the proportion was almost the opposite. .

Complete immunization schedules

However, another thing (and many) worries about Delta: ¿how vaccines work to the mutations that this variant causes ?. There is bad news, but the last week has also brought good news. The bad are in the procurement and delivery of vaccines, as there is a big difference in the protective action achieved with a dose or two. Analyzes from England and Scotland indicate a reduction in vaccine efficacy for Delta compared to Alpha. This is most pronounced when the person has applied only one dose of both programs.

“The evidence indicates that IVaccines are effective enough to reduce hospitalizations and deaths among those vaccinated ”, indicates the Covid-19 vaccine surveillance report, released this week in the UK. Experts estimate that the reduction in hospitalizations among those who received a dose would be between 26% and 40%. For those who completed both doses, the drop was between 76% and 84%.

And that’s why the ruling in this country is reduce the waiting interval between the first and second dose of vaccine. The 12-week wait strategy (also adopted in Argentina and Canada, among other countries) is linked to accelerating the vaccination of more people. This, in turn, was due to two realities: the insufficient number of doses to complete the vaccination schedules between 21 and 28 days, the fact that in the case of the AstraZeneca vaccine, various studies have shown greater efficacy after 12 weeks from the first bite, and the need to at least partially vaccinate as many of the population as possible.

As the first doses of the vaccines continue to be effective with Delta, but less, it was decided to reduce this wait to 8 weeks instead of 12. This decision has already been made in Canada and is expected in the UK.
In Argentina, the current recommendation of 12 weeks is maintained, but with the aim of accelerating the vaccination of second doses of all vaccines applied in the country.

And the highlight is that Delta may soon become the most dominant variant of the pandemic coronavirus in the world and cause a rapid increase in new cases of Covid-19 in countries that still have very low or near zero vaccination rates. At Africa for example, it is believed that recently by the end of the year 10% of the population will have been vaccinated.

Are vaccines useful?

Recent research from the UK government has found that the full vaccination is still effective against Delta, although less so than other variants, especially with a single dose.

Based on data from Public Health Scotland Posted in The Lancet, at least two weeks after the second dose of the covid vaccine, the protection against infection increased from 92% for the Alpha variant to 79% against the Delta variant for the product of Pfizer / BioNTech, while for the vaccine Oxford / AstraZeneca protection increased from 73% to 60%. In the case of a single dose, protection against symptomatic disease would only be between 33.5% in the case of Delta, while for Alpha it is 51%.

However, this week brought good news in terms of protection against severe forms of Covid-19. In hospitalizations, vaccination would offer similar protection against both variants, at least with Pfizer / BioNTech (94% with one dose and 96% with two) and AstraZeneca (71% and 92%) against the Delta variant. The Gamaleya Institute of the Russian Federation assures that a work showing a high efficacy of the vaccine has already been sent to a scientific publication Sputnik V Against this variant which, despite the fact that there are already several countries that lift the restrictions, is causing concern among the population.