New study on Covishiled claims that neutralising antibodies against the Delta variant (B1.617.2) of Covid-19 were not found in 16.1 per cent samples from those who had been administered both doses of the vaccine. Further, neutralising antibodies were not observed in 58.1 per cent of serum samples from those who had been given only one shot of Covishield.
The recent emergence of B.1.617 lineage has created grave public health problem in India. The lineage further mutated to generate sub-lineages B.1.617.1 (Kappa), B.1.617.2 (Delta), B.1.617.3. Apparently, the Delta variant has slowly dominated the other variants including B.1.617.1 (Kappa), B.1.617.2 (Delta), B.1.617.3. With this, World Health Organization has described this sub-lineage as variant of concern. The high transmissibility associated with Delta variant has led to second wave of pandemic in India which affected millions of people.
In a recent video address World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus while speaking about the Delta variant of the coronavirus said “Compounded by more transmissible variants, like Delta, which is quickly becoming the dominant strain in many countries, we are in a very dangerous period of this pandemic,” Ghebreyesus said. “But no country is out of the woods yet. The Delta variant is dangerous and is continuing to evolve and mutate, which requires constant evaluation and careful adjustment of the public health response,” he said. The Delta variant of the virus was first detected in India. Watch the full video for more details.
Delta, which is quickly becoming the dominant strain in many countries – WHO Director General
Dr T Jacob John, former head of the department of microbiology at Christian Medical College in Vellore was quoted in the Hindustan Times, “Not observed is not equivalent to not present. The levels of neutralising antibodies could be significantly low such that it did not get detected, but it may still be there and protect the person against infection and severe disease. Also, there would be some cell mediated protective immunity as well that can protect the individual.”
“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 or have chronic diseases since their immune response is lower. What this means is that men (women produce higher levels of antibodies) 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 John explained.
The titres of the neutralising antibodies – that specifically target the Sars-CoV-2 virus and kill it or prevent it from entering human cells – were also lower against the Delta variant as compared to the B1 variant that led to the first wave of infections in India. As compared to B1, the neutralising antibody titres against the Delta variant were 78% less in those who received one shot, 69% in those who received two shots, 66% in those who had the infection and received one shot, and 38% in those who had the infection and received both shots.
“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 (women produce higher levels of antibodies) 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,” said Dr Jacob John.
He added, “On the other hand, one dose is more than enough for an immune response in those who have had the infection.”
