Delta decoded: A brief on the lethal mutated SARS COV 2 virus

With reports pouring in from over the world on its the rapid spread, it is being acknowledged as the dominant variant today. Owing to its high transmissibility and contagious nature, this variant has surpassed all other existing SARS COV 2 variants in its lethality. Noting the alarming rise in cases of Delta-plus globally ,the WHO classified this lineage 'variant of concern'(VOC) on 11 May 2021, and highlighted on its higher transmissibility and reduced neutralisation. Subsequently in India, the Ministry of Health and Family Welfare declared it to be a 'variant of concern'(VOC) on 22 June, 2021 .What is Delta-plus?

The Delta plus variant, technically named B.1.617.2.1 or AY.1, belongs to the lineage of Delta SARS COV 2 virus, which is responsible for the ongoing 2^nd wave of the pandemic across nations. Since its onset in 2019, the coronavirus has undergone multiple mutations . The B.1.617 lineage consists of B.1.617.1(Kappa), B.1.617.2(Delta), and B.1.617.3 (Double mutant). Further modification in the B.1.617.2 Delta variant, along the K417N spike protein of the viral structure, a specific mutation on the tip of the viral spike, has been responsible for the origin of the deadlier Delta-plus.

According to a report published in India Today, experts are of the opinion that the Delta variant is 40 to 100 per cent more transmissible than the Alpha variant. A recent press release by MoHFW has affirmed that Delta Plus has increased transmissibility, stronger binding of the virus to receptors of lung cells and potential reduction in response to a potential drug against the virus.

• Origin of Delta-plus-

Key mutation that marks out the Delta-plus variant from the original Delta variant — called the K417N mutation — was first identified in Nepal. While initial samples of this variant were isolated in Europe in March, England reported it by April-end among patients who were contacts of individuals travelling from Nepal and Turkey.

In the words of executive director of the WHO's health emergencies program, the original Delta variant , first identified in India by late 2020. , has the potential "to be more lethal because it's more efficient in the way it transmits between humans and it will eventually find those vulnerable individuals who will become severely ill, have to be hospitalized and potentially die."

Global scenario of the new Delta-plus

The presence of the new strain has now been confirmed from nine countries - US, UK, Portugal, Switzerland, Japan, Poland, Russia and China ,besides India.

According to the WHO, the mother Delta variant has now been reported from about 75 countries. In countries such as the UK, it has emerged as the most dominant variant of Sars-2.In the US, the Delta variant has shown a sharp spike in spread from about 10 per cent to over 30 per cent in the past one week. Surveillance studies from the U.S., Germany and the Netherlands indicates the Delta variant is growing by about a factor of 2 to 3 every two weeks with respect to the Alpha variant, with chances of it spiking as the dominant variant around July in these countries.

Indian Scenario with Delta and Delta Plus:

In India, over 40 cases of Delta Plus have already been identified from Maharashtra's Ratnagiri and Jalgaon; in Palakkad and Pathanamthitta in Kerala; and in Bhopal and Shivpuri in Madhya Pradesh. The centre has urged on taking emergency steps and instructed the states to take "immediate containment measures" , along with the continuing rapid tracing and isolation measures.

According to Indian SARS-CoV-2 Genomic Consortia (INSACOG), a consortium of 28 labs tasked with genome sequencing of the virus causing Covid, "Currently the number of such Delta plus variants in India are only few but the distribution/detection in various states during past two months indicate that it is already present in some states and states may need to enhance their public health response by focusing on surveillance, enhanced testing, quick contact-tracing and priority vaccination."

Will Vaccines work against Delta plus?

Addressing on the efficacy of the current vaccination drive ,the central government has stated that the two vaccines being used in India, Serum Institute of India's Covishield and Bharat Biotech's Covaxin, are effective against the Delta variant; data on how they work on the Delta Plus is being investigated and will be shared soon. Amidst rising concern among scientists that the Delta Plus variant could be even more transmissible than the Delta variant, early "evidence of the Delta-plus variant's "resistance to monoclonal cocktail antibodies Casirivimab and Imdevimab" has been confirmed by CSIR and Institute of Genomics and Integrative Biology (IGIB).

Nation like UK and US have been observing secondary attack rates as high as 51–67% in comparison to the previously widespread Alpha variant. In such conditions, the protective effect of antibodies remains a matter of debate.

Amidst rising concerns on whether the Delta plus strain will eventually lead the way to a more dangerous third wave, the only hope rests on breakneck speed research work going on worldwide to curb this fast expanding strain.