Do vaccines work against Covid’s Delta variant? Know all about immunity evasion & war against newer mutations

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Updated: September 08, 2021 2:10 PM

A study published in the journal Nature has found SARS-CoV-2 Delta variant to readily evade the immune response gained through previous infections or vaccines.

Delta variants are eight times less unresponsive to vaccine-induced antibodies

The Covid-19 Delta variant of the SARS-CoV-2 virus with a much higher ability to infect and transmit between individuals is now found in 170 countries, says the World Health Organisation. The Delta variant, or the B.1.617.2 lineage, was first discovered in Maharashtra and was mostly responsible for causing the second surge in the country.

Now, a study published in the journal Nature has found this particular variant to readily evade the immune response gained through previous infections or vaccines. The data was collected from India till the end of May and research was. Carried out by international and Indian researchers.

Key findings of the study for Delta variant of SARS-CoV-2

The study found that the Delta variants are eight times less unresponsive to vaccine-induced antibodies and six times less unresponsive to serum-induced antibodies from past reactions.

This means the Delta variant is six times more prone to break the natural immune response of the body acquired through previous infections and eight-time is more likely to break the vaccine protection and cause infection among the vaccinated people. The vaccines that were used for the research are widely used AstraZeneca/Oxford University vaccine and Pfizer by BioNTech.

The study also reported “replication and spike mediated entry” which means it has a greater ability to infect and reproduce and multiple inside the human body compared to the original B.1.617.1 lineage first found in Wuhan.

The study examined 130 cases of breakthrough infections in fully vaccinated healthcare workers during the second wave at three Delhi hospitals and found that the vaccine efficacy is less for this particular variant.

Anurag Agrawal, director of the Delhi-based CSIR-Institute of Genomics and Integrative Biology, and a joint author of the study said that although the Delta variant does spread faster and reduces protection from the vaccine, jabs leads to reduced severity of the condition.

Other studies on the effectiveness of vaccines against Delta?

Four other studies cited by WHO also have come up with the same conclusion that the Delta variant is less sensitive to vaccines and natural immunity. One of these studies conducted in the UK finds reduced effectiveness of Covishield in a period when the Delta variant was the most dominant in the country, compared to its predecessors, the alpha variant in the first wave.

What grounds do vaccines hold in time of Delta variant

Vineeta Bal, an immunologist with the Indian Institute of Science Education and Research (IISER) in Pune told the Indian express that the study should not lead people to doubt vaccinations as the study comes with its limitations .

Bal pointed out that the study was conducted out on in vitro samples in a laboratory environment, the evaluations cannot be conclusive as they were not conducted inside the human body. Such neutralising antibodies don’t provide the entire answer, he said.

Bal further reasoned that in the human body, immunity is provided by both neutralising antibodies and T-cell responses. Since the study does not show data on how T-cells respond to the Delta variant, it leaves a major component of immune response out of considerations, making the study short of being all-inclusive.

The immunologist further said that the outcomes were not surprising as most of the infections today post-vaccination or re-infection are from the Delta variant. He further claimed that no vaccination can provide 100 per cent protection but can lower hospitalisation and severity among the infected people.

According to Anu Raghunathan, a scientist at the National Chemical Laboratory in Pune, the study concludes that a larger amount of antibodies, about five to eight times more than what is required for the Alpha variant is required to block the Delta variant or get the same kind of immune response.

How to deal with newer variants now?

According to experts the only way to slow down the formation of the mutation of the virus and form new variants is to reduce the spread of the infections through measures like vaccination or observance of Covid-appropriate behavior.

Raghunathan said that the need of the hour is a continuous assessment to find out the behaviour of new variants, antibody response against them and assessing the need for booster doses of vaccine to create a higher amount of antibodies or updating the formulation of the vaccines depending on new variants. Genomic sequencing of new variants should also be rampant, he added.

In the current context of the emergence of Delta variant, she said the need for a booster dose of vaccine should be considered and newer,more effective vaccines should be readily made available in the market as they come.

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