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Delta Variant Responsible for India's Second COVID-19 Wave Has High Virulence Rate, Says Expert

© REUTERS / DANISH SIDDIQUIPatients suffering from the coronavirus disease (COVID-19) are seen inside the ICU ward at Holy Family Hospital in New Delhi, India
Patients suffering from the coronavirus disease (COVID-19) are seen inside the ICU ward at Holy Family Hospital in New Delhi, India - Sputnik International, 1920, 04.06.2021
The second wave of the coronavirus pandemic has ravaged India as official figures suggest over 28 million COVID-19 cases and over 300,000 deaths in the country while experts hint that the actual numbers are much higher.

The Indian SARS-CoV-2 Consortium on Genomics (INSACOG), announced on Friday that the Delta variant (B.1.617), and its lineage B.1.617.2, have a high transmissibility rate, at 50 percent above the Alpha variant (B.1.1.7). The Delta variant is the primary cause of the second COVID-19 wave in the country.

Last year, the country's Health Ministry established INSACOG, a group of 10 national laboratories. Since then it has been carrying out genomic sequencing and analysis of circulating COVID-19 and correlating epidemiological trends with genomic variants.

Sputnik reached out to Dr. Saher Mehdi, co-founder & chief scientist, wellOwise, and she said that there are three known subtypes of the SARS-CoV-2 variant of B.1.617 that was first reported in India last year. The original variant, known as B.1.617.1 (the ‘original’ B.1.617), is a 'variant of interest (VOI)', the B.1.617.2 recently renamed as the Delta variant, is the 'Variant of Concern (VOC)' and the B.1.617.3 has not yet been designated as a class by the World Health Organisation (WHO).

Covid Variants

A woman walks past graffiti on a street, amidst the spread of the coronavirus disease (COVID-19) in Mumbai, India, 10 May 2021 - Sputnik International, 1920, 01.06.2021
WHO Names COVID Variants Using Greek Alphabet to 'Lose Stigma' over Country of Origin
To avoid stigmatising nations, the WHO on Monday announced that the variants of COVID-19 will now be known by a letter of the Greek alphabet. The Covid variant of B.1.617, first detected in India, is split into sub-lineages, of which the B.1.617.1 variant of interest has become 'Kappa'. The B.1.617.2 variant of concern is called 'Delta'.

"We know that the Delta variant does have increased transmissibility, which means it can spread easier between people," WHO's technical lead on Covid-19, Maria Van Kerkhove, told reporters on Tuesday.

During the first wave, most people were infected by the original B.1.617.1, whereas in the second wave, the Delta variant was the cause of most COVID-19 cases.

Delta - The Variant of Concern

According to an INSACOG study, the rise in prevalence of the Delta variant was accompanied by a rise in the overall rate of infections. The study also mentioned that the rise in COVID-19 deaths was due to the collapse of the Indian healthcare system and not directly because of the variant.

"The Delta variant (B.1.617.2) has two distinct mutations called L452R and 478K, both of which are linked to increased transmissibility, virulence, and decreased effectiveness against known diagnostic and therapeutics. These mutations alter the spike protein, which the SARS-CoV-2 uses to enter the human cells," Mehdi told Sputnik.

Mehdi also said that this variant has a high virulence rate and the presence of T478K mutation in the Delta variant (B.1.617.2) could be the cause of its high transmissibility. The other two subtypes, however, do not have this mutation.

Per media reports, the latest cases of the Delta variant of COVID-19 have now been reported in the UK and in the Australian city of Melbourne. 

On the impact of the Delta variant, if a possible third wave of COVID-19 comes, Mehdi said: "There is not enough data from modeling studies to predict the third wave. We may see many more mutations of the variant in future, but whether they will be as virulent as B.1.617.2, no one can predict that."

In April, the COVID-19 outbreak in Delhi was preceded by other outbreaks in Kerala, Maharashtra, and Punjab. While no variant of concern was identified in Kerala in January, the outbreak in Maharashtra has been connected to the B.1.617.1 and in Punjab to the introduction of B.1.1.7. 

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