The Delta variant has been found to be eight times more resistant to vaccine antibodies. According to scientists, Delta Plus has an extra mutation called K417N in the spike protein that enhances the attachment of the virus to infected cells. This mutation increases chances of the virus to escape immunisation and can influence vaccine effectiveness.
A collaborative study, 'SARS-CoV-2 B.1.617.2 Delta Variant Emergence and Vaccine Breakthrough: Collaborative Study', from India researchers with scientists from Cambridge institute of Therapeutic Immunology and Infectious Disease stated that in vitro, the Delta variant was approximately eight times less sensitive to vaccine-elicited antibodies as compared to the original variant. The results of the study revealed that across all the scenarios considered, the Delta variant is both more transmissible and better able to evade prior immunity caused due to previous infection. Thus, even individuals who have gotten both doses of the vaccine should not lower their guard and keep maintaining precautions. Due to the current variant's enhanced spike proteins, it gives the virus greater ability to attach to the lung epithelial cells, thus giving it the ability to infect a larger number of people than the initial variant found in Wuhan.
The current prevalence of the Delta variant in India is speculated to have been driven by the evasion of neutralising antibodies in previously infected individuals and the increased infectivity of the virus which resulted in the second wave.
Based on recent data on the Delta infections, the B.1.167.2 Delta variant appeared to be more transmissible than the B.1.1.7 in the UK. Additionally, the study predicted that the new variant would have a transmission advantage in comparison to the Wuhan-1 in individuals with pre-existing immunity from vaccine/natural infection in settings where there is low vaccine coverage.
A new study conducted by researchers from the Indian Council of Medical research claims that neutralising antibodies against the Delta variant B.1.617.2 were not found in 16.1 per cent of the samples who had been administered both doses of the Covishield vaccine.
However, progression to severe disease and death was low in all studies. Thus, at the population scale, extensive vaccination is still expected to protect against moderate to severe disease and reduction in hospitalisation rates, related to the Delta variant.
(Edited by Pronoy Basu)
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