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Delta variant: what we know about the Covid-19 strain first discovered in India


The B.1.617.2 strain, officially known as the Delta variant, is of concern to health officials across the world, including in the United States. The Delta variant now accounts for more than 6% of virus samples sequenced in the United States, according to data from the United States Centers for Disease Control and Prevention.

While that may seem like a relatively small share, the speed of its growth is of concern. A month ago, the strain made up just over 1% of virus samples sequenced, according to CDC data.

Experts believe the Delta variant sparked the huge wave of infections seen in India over the past two months. It now worries the United Kingdom, where it now accounts for 91% of new cases, according to Health Secretary Matt Hancock.

The spread of the variant’s spread came alongside a sizable spike in the number of UK cases in recent days, a spike that has prompted the government to deploy the military to the hardest-hit areas to help run testing and traceability. program.

The World Health Organization (WHO) designated B.1.617 and its sublines, including B.1.617.2, as “variants of concern” on May 10th. This classification means that a variant may be more transmissible or cause more serious disease, not respond to treatment, escape the immune response, or go undiagnosed by standard tests.

The Delta variant was the fourth to be declared a “variant of concern” by the WHO; the others are B.1.1.7, which was first seen in the UK and is now known as the Alpha variant; B.1.351, or Beta, first detected in South Africa; and P.1, first found in Brazil and now called Gamma.

Here’s what you need to know.

Is it more contagious?

Experts now believe the Delta strain is probably more transmissible.

Hancock said last weekend that the strain was “about 40% more transmissible” than the once-dominant Alpha variant, which was already more transmissible compared to the original strain of the virus.

Speaking at a White House briefing on Covid-19 on Tuesday, the director of the National Institute of Allergy and Infectious Diseases, Dr Anthony Fauci, said studies support the idea that the strain is more transmissible.

“It’s clear now that its transmissibility appears to be greater than that of wild type,” Fauci said, adding that the strain’s 6% share in the US is similar to a tipping point previously seen in the UK.

“It’s a situation, as was the case in England where they had a dominant B.1.1.7, then the [B.1.] 617 took over. We can’t let that happen in the United States, ”Fauci said.

Is it more deadly?

Early evidence suggests that the Delta variant may carry an increased risk of hospitalization compared to the Alpha strain, according to Public Health England (PHE).

While PHE warned that more data is needed, its initial findings showed that people infected with the variant were more likely to suffer from serious illness. An analysis of 38,805 cases sequenced in England showed that people infected with the Delta variant had 2.61 times the risk of hospitalization within 14 days compared to the Alpha variant, when variables such as age, Gender, ethnicity and vaccine status were taken into consideration, PHE said last week.

Fauci echoed the concern, saying the variant “could be associated with increased severity of the disease. “

Do vaccines work against?

There is evidence that existing Covid-19 shots work against the Delta variant.

A team of researchers from BioNTech and the University of Texas medical branch reported on Thursday that they had found evidence that the Pfizer / BioNTech vaccine would protect against infection with the Delta variant and others.

They tested the blood of 20 fully vaccinated volunteers against lab-engineered versions of several virus variants and found evidence that the immune system should neutralize them.

UK-based researchers reported last week that most people who receive two doses of the Pfizer / BioNTech coronavirus vaccine would still have protection against the new variant, although they said the antibodies appeared to be significantly reduced.

Hancock also said that research so far suggests that “after two doses of the vaccine, we are confident that you get the same protection as with the old variant.”

People need to be fully immunized to be fully protected. Researchers at the Francis Crick Institute and the National Institute for Health Research (NIHR) UCLH Biomedical Research Center also said that after a dose of the vaccine, people were less likely to develop an antibody response sufficient to protect against the Delta variant, compared to the previously dominant variant.

In a press release accompanying their research, the scientists said their results suggest that the best way to combat the new variant is “to deliver second doses quickly and provide boosters to those whose immunity may not be. quite high against these new variants “.
The first data published by PHE showed similar results for the AstraZeneca and Moderna vaccines. They too appeared to be effective against the Delta variant once both doses were given.

Which countries have detected the variant?

The variant has been identified in 74 countries, on all continents except Antarctica, the WHO said in its latest weekly epidemiological update released on Tuesday.

It is spreading very quickly – a month ago the WHO said it was present in just over 40 countries.

Other variants quickly spread across the world, including new variants that were no more heritable than established lines. The researchers note that sometimes a dominant strain is simply the strain that rides a wave of transmission fueled by travel and mixing.

What does this mean for global roadmaps out of lockdown?

The UK, where the Delta variant is now dominant, is a bit of a warning to the rest of the world. Neil Ferguson, an epidemiologist at University College London, said on Wednesday that the variant could lead to a “substantial third wave” of Covid-19 infections in the UK.

The rapid spread of the Delta variant has prompted France and several other countries to impose new restrictions on travelers from the UK.

This has already raised fears that the UK government’s plan to lift remaining restrictions on coronaviruses on June 21 could worsen the spread. Hancock said the government was closely monitoring the data to determine its next steps.

The outbreak in India has also had an impact on the global vaccine supply. India is one of the major vaccine manufacturers, but when cases started to rise, its government restricted the export of Covid-19 vaccines.

And the more the virus spreads, the more likely it is to mutate and evolve into new variants that could possibly resist current vaccines, threatening to undermine the progress of other countries in containing the pandemic.

CNN’s Maggie Fox, Niamh Kennedy, Eleanor Pickston, Kara Fox, Robert Iddiols, Virginia Langmaid and Aditi Sangal contributed to this report.

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