Explainer-Delta dominates the world, but scientists take care of disturbing offspring Reuters

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Author: Julie Steenhuysen
CHICAGO (Reuters) – The Delta variant of the SARS-CoV-2 virus now covers almost all coronavirus infections worldwide, spreading to many parts of the world without the spread of the novel coronavirus. To date, vaccines are still able to protect against serious diseases and deaths in the Delta, but scientists remain on alert.
Here’s what we know:
DELTA – STILL MAIN
The Delta variant, first detected in India in December 2020, remains the most disturbing version of the SARS-CoV-2 virus.
The World Health Organization classifies Delta as a variant of worrisome, which means that the variant is able to increase transmissibility, cause a more serious disease, or reduce the benefit of vaccines and treatments.
The “superpower” of the delta is its transmittance, according to Shane Crotty, a virologist at La Jolla Immunology Institute in San Diego.
Delta is twice as contagious as the previous SARS-CoV-2 variant, according to the U.S. Centers for Disease Control and Prevention. Research suggests that infected people are more likely to be hospitalized than previous forms of the virus.
The delta can also cause symptoms two to three days earlier than the original coronavirus, and can give the immune system less time to assemble a defense.
People infected with the delta carry 1,200 times more viruses on their noses than the original version of the coronavirus. The number of people with vaccines infected with the delta is comparable to those without vaccines, and both can transmit the virus to others.
In people who have been vaccinated, however, the number of viruses drops faster, so it is likely that the virus will spread in a shorter time.
According to the WHO, Delta accounts for 99.5% of all genomic sequences reported in public databases and has “competed” with other variants in most countries.
A key exception is South America, where the Delta has spread more slowly, and other variants previously seen as possible global threats – Gamma, Lambda, and Mu in particular – still contribute a large proportion to the reported cases.
DELTA CHILDREN
Given the global dominance of the Delta, many vaccine experts believe that all future variants will be descended from the Delta.
A notable Delta “grandson” is known as AY.4.2 and is concentrated in the United Kingdom, where approximately 10% of sequenced virus samples.
AY.4.2 carries two additional mutations in the peak protein that the virus uses to enter cells. Scientists are still studying what advantages these mutations provide.
The UK Health Safety Agency has designated AY.4.2 as a “variant under investigation”. A preliminary analysis suggests that it does not significantly impair the effectiveness of the vaccine compared to Delta, but it has been shown to be slightly more transmissible, the agency said.
According to the WHO, AY.4.2 has been extended to at least 42 countries, including the United States.
MORE ON THE WAY?
Virus experts are watching closely the evolution of the Delta, a highly transmissible variant looking for signs that it has acquired mutations that would allow it to puncture the immune protection of vaccines and natural infection.
However, although current vaccines prevent serious illness and death, they do not block the infection. The virus is still able to replicate in the nose, even among people who have been vaccinated, and can then transmit the disease through small aerosolized drops.
Defeating SARS-CoV-2 will likely require a new generation of vaccines that block transmission, according to Dr. Gregory Poland, the developer of vaccines at the Mayo Clinic. Until then, Poland and other experts say the world remains vulnerable.
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