PremiumA new study by the researchers from the Indian Council of Medical Research (ICMR) has claimed that neutralising antibodies against the Delta variant of coronavirus was not observed in 16.1% of those who had been administered both doses of the Covishield vaccine.
On the other hand, the neutralising antibodies were not observed in 58.1% of serum samples from those given one shot of the Serum Institute's Covishield, a report in Hindustan Times added.
As per the report, the titres of the neutralising anitbiodies that specifically target the Covid-19 virus (Sars-CoV-2) from entering human cells were lower against the Delta variant as compared to the B1 variant that led to the first Covid wave in the country.
As compared to B1, the neutralising antibody titres against the Delta variant were 78% less in those who received one Covid jab, 69% in those who received two shots of Covishield, 66% in those who had the infection and received one shot, and 38% in those who had the infection and received both shots.
The daily quoted Dr T Jacob John, former head of the department of microbiology at Christian Medical College-Vellore and said, "Not observed is not equivalent to not present".
However, Dr Jacob added that there would be some cell mediated protective immunity as well that can protect against infection and severe disease.
Assuming that the serum used for the study was from healthy individuals, the proportion of individuals with unobserved levels of neutralising antibodies will be higher among those who are old, comorbid, have chronic diseases as their immune response is lower. What this means is that men and women over the age of 65 years, those with diabetes, hypertension, chronic heart, lung, kidney diseases, or who are undergoing treatment for cancer should be given a third dose, Dr Jacob added.
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