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New Delhi: ICMR researchers have found that the derivatives (sub-lineage) of the SARS-CoV-2 delta variant have the potential to reduce the neutralization ability of the Kovidhield vaccine, especially in people who have never been infected with COVID.
team, a. based on the findings of Study In blood samples from vaccinated individuals, a booster dose has been recommended for those who have already been vaccinated.
The spread of the delta variant in India caused a devastating second wave and cases have also increased across the world.
“The delta variant gradually came to dominate other forms of concern. Thereafter, delta further changed from delta AY.1 to delta AY.126. Of these, delta AY.1 has been reported from several countries including India , and is considered a highly infectious and likely escape mutant,” the researchers wrote in the study.
The escape mutant is the one that can escape the human immune response or the vaccine-induced immune response. Researchers previously evaluated Effect Delta of Covaxin against AY.1 (as it is an escape mutant) and found the vaccine to be effective.
Posted in latest study biorxiv (A repository of pre-print studies) On Thursday, researchers evaluated the neutralizing efficacy of blood samples from people who had received two doses of the Covishield vaccine.
The study has yet to be reviewed.
The researchers said, however, that with a low neutralization capability, CoveShield would protect against serious illness and fatalities.
Read also: Covaxin, Covisheeld effectiveness highest when gap between doses is 6-8 weeks, ICMR study finds
neutralizing immune escape variants
Researchers studied three types of blood samples. The first was from people who had been fully vaccinated from Kovidshield, and had never been infected with Covid. The second was from people who had previously been fully vaccinated after recovering from a Covid infection. The third was from people who became infected with COVID after being fully vaccinated – people who had a breakthrough infection.
The blood samples were tested against delta and two of its derivatives – delta AY.1 and B.1.617.3, known as the 50 percent plaque reduction neutralization test (PRNT50). In this test, a blood serum sample is diluted and mixed with a viral suspension. The mixture is then discarded to allow the antibodies to react with the virus.
It is then poured over a layer of host cells, usually in a Petri dish. On the surface of the cell layer there is a layer of jelly-like substance called agar to prevent the virus from spreading.
Researchers estimate areas of infected cells — called plaques — form after a few days. This can be done either by microscopic observation or by using specific dyes that react with infected cells.
The concentration of serum needed to reduce the number of plaques by 50 percent determines how much antibody is present or how effective it is. This measurement is represented as the PRNT50 value.
The researchers found the greatest reduction in the level of neutralizing antibodies against the delta variant – a 27.3-fold reduction – in fully vaccinated individuals who had never been infected with COVID, compared to other groups and variants.
Neutrality was reduced against Delta and AY.1 in all three groups.
Read also: ‘Covidshield gap, sky won’t fall’ as vaccines pile up, members of the Covid task force say
Vaccines will protect against serious illness, death
However, the team said that the vaccines would continue to provide adequate protection against disease severity and lethality, based on the infection data they analyzed.
The team noted in the study, “Several studies have reported increased immune response in COVID-19 recovered cases and successful infection following vaccination.”
He added that such an increase in the immune response actually helps in effectively neutralizing the escape forms of immunity in successful cases of COVID.
The team said, “Once a person is re-infected after vaccination or vaccination, memory B cells (a type of white blood cell involved in the immune response) are triggered which generate a high level of immune response. are,” the team said.
The team concluded that “our findings suggest that the Covishield vaccine was able to neutralize the delta derivatives and prevent severe disease and lethality in breakthrough cases,” the team said.
He said that a booster dose vaccination among fully vaccinated people, who have never been infected with COVID-19, will elicit a protective immune response to fight against the emerging SARS-CoV-2 variants.
(Edited by Polomi Banerjee)
Read also: Supply of ZyCov-D will begin soon, but it may not be part of the national vaccine program yet
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