First Indian strain
Delta (B.1.617.2) is a new variant of the SARS-CoV-2 coronavirus, first discovered and
On June 16, 2021, Medvestnik reported that the shareIndian delta strain (B.1.617 according to Pango classification) has accounted for 63.2% in Russia over the past four weeks, as indicated on the international GISAID platform, which provides open access to the genomic sequences of influenza and coronavirus viruses and geographic data on the distribution of coronavirus variants.
In the database of the Berne and Basel projectsUniversities of Switzerland CoVariants indicated that the share of the Indian delta strain from sequenced samples was 66% in Russia in the second half of May 2021.
According to the Russian Consortium forsequencing of SARS-CoV-2 genomes (Coronavirus Russian Genetic Initiative, CoRGI), the Indian delta variant accounted for slightly more than half (52%) in samples obtained in May, and more than 90% in June 2021.
Second Indian strain
On June 14, 2021, India was discovereda mutated variant of B.1.617.2, which is known as variant AY.1 or delta +. Delta + is distinguished by the presence of the K417N mutation in the spike protein, which can reduce the activity of antibodies in recovered and vaccinated people.
The Ministry of Health does not yet classify it as a mutation of concern. It is named "Delta Plus" because it uses eight spike protein mutations, while the usual "delta virus" only uses six.
State government officials said more samples of the virus have been sent for genome sequencing, with plans to find out if the new variant is dominant.
To contain the spread of the coronavirus, authorities have created special zones and sealed areas where a new variant of the coronavirus was discovered.
Where did both strains come from?
The delta variant was first discovered in Indialast fall - the first genome was published in the international GISAID database on October 7, 2020. This, however, does not mean that the new variant of SARS-CoV-2 originated in the same country; the strain was only discovered in India.
The first cases of delta + infection were reported in four districts of the state of Maharashtra in central India
Why are Indian strains dangerous?
The first Indian strain has many mutations.The delta variant is now known to be six times more infectious than the Wuhan, UK, South African and Brazilian strains. It caused a record epidemic in India this spring and is now spreading in many countries, displacing other strains.
According to GISAID, the leaders in the number of Indian strains sampled are Great Britain, USA, Germany, Singapore, Canada and Russia.
The delta characteristic of the variant is notedmutation P681R in the region of the so-called “furin insertion” common to all variants. This insert is a small fragment of the S protein in which it can be cut before entering the cell.
Proponents of laboratory origin of SARS-CoV-2consider this insertion as one of the arguments in favor of the fact that the virus was artificially “improved” by researchers who were trying to make it more infectious to human cells.
The reasoning was based on the fact that this furinthe insert is not present in the closest relatives of SARS-CoV-2, but at the same time it facilitates the cutting of the S-protein and affects the infectivity (a similar site, however, is found in other coronaviruses).
The main thing that distinguishes the delta option from delta+ is— mutation K417N. This is a mutation in the spike protein gene that leads to the replacement of the amino acid lysine (K) with the amino acid asparagine (N) of this protein at position 417, which is located in the so-called receptor-binding domain (RBD), which is responsible for binding virion with receptors on the surface of human cells, said Konstantin Krutovsky, professor of the Department of Genomics and Bioinformatics of Siberian Federal University, professor of the University of Göttingen.
How much did the strains spread across Russia?
- Delta
In Russia, according to the open Russian consortium for sequencing SARS-CoV-2 genomes, in May Delta accounted for slightly more than half of all cases (52%), and in June - more than 90%.
These data, however, were obtained as a result ofresearch only in St. Petersburg. The growing spread of Delta in Russia is also evidenced by the data of the international monitoring of the Nextstrain.org portal:
Data analyst Sergey Shpilkin based on dataGISAID, which studies the genomes of viruses, calculated that the proportion of the Indian strain in Russia doubles every 5-6 days. “Without taking additional measures, we will have a doubling of the number of cases in those same 5-6 days.
- Delta +
According to Indian media, 36 samples,containing the Delta Plus genome were found in England. Other cases have been linked to travel to Nepal, Turkey, Malaysia and Singapore. Also, some samples came from Europe and America, which indicates the widespread prevalence of this variant. There have been no reports of delta+ infection in Russia at the moment.
Differences in symptoms
The Indian strain of coronavirus is completely differentsymptoms. In the UK, where the Delta strain has become dominant, patients now most often complain of headache, sore throat, fever and runny nose.
Symptoms of classic covid are loss of smell anddry coughs are now much less common, which makes the coronavirus easy to mistake for a cold or the common flu, writes The Mirror, citing scientists from King's College London.
The source of talk that the infectionthe delta variant leads to slightly different symptoms than infection with other variants of SARS-CoV-2, Tim Specter, an employee of King's College London, apparently became. Specter's words, however, have not yet been confirmed either by scientific publications or even Symptom Tracking Project press release.
Rospotrebnadzor said that when infectedwith the Delta strain, patients complain of abdominal and joint pain, nausea, and loss of appetite and hearing. Experts refer to the data of Indian doctors: in India, patients often have diarrhea, while fever, cough and loss of smell are less common.
Do vaccines against Indian strains work?
The delta variant is also capable of partially escapingnatural and vaccine immunity, which is manifested, for example, in the fact that one vaccination for reliable protection in his case is not enough; it occurs only after the administration of the second dose.
Fully immunized people stillprotected from the severe course of the disease, although a slight decrease in effectiveness (relative to the onset of symptoms) is seen in statistics for such people.
WHO urges to wait for moredetailed studies - so far there is no evidence that vaccines do not work. However, Russian scientists said on June 18 that new mutations in the coronavirus are reducing the effectiveness of vaccines developed and tested against earlier strains.
The head of BioNTech, Ugur Sakhin, in April alsostated that he was confident in the effectiveness of the Pfizer vaccine against the Indian strain. However, CNBC notes that at that time the company did not have sufficient data on the delta option.
According to Indian scientists, delta+ evades treatment with monoclonal antibodies against COVID-19. But this still needs to be proven.
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