A new study stated that the breakthrough cases of COVID-19 and the recovered patients with one or two doses of vaccine have shown comparatively higher protection against Delta variant in comparison to those administered either one or two doses of Covishield.
According to the study which is yet to be peer-reviewed and was posted on bioRxiv preprint server on Friday noted that earlier vaccination results in less disease against the following infection provide signals that both humoral and cellular immune response plays an important role in protection.
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), and B.1.617.3. Apparently, the Delta variant has slowly dominated the other variants. With this, the World Health Organisation has described this sub-lineage as a variant of concern,” the study stated.
The study ‘Neutralisation of Delta Variant with Sera of Covishield vaccines and COVID-19 Recovered Vaccinated Individuals’ has been conducted by scientists from the Indian Council of Medical Research (ICMR), National Institute of Virology, Pune, and Department of Neurosurgery, Command Hospital (Southern Command), Armed Forces Medical College, Pune.
“The high transmissibility associated with Delta variant led to second wave of the pandemic in India which affected millions of people. Besides this, variant of concerns has been reported to show lower neutralisation to several approved vaccines. This has led to breakthrough infections after completion of vaccination regimen,” it said.
However, there is limited information available about duration of defensive immune response post-infection, vaccination or breakthrough infection with SARS-CoV-2. The study estimated that immune response in vaccines of the Covishield vaccinated individuals belonging to categories– one dose vaccinated, two doses vaccinated, COVID-19 recovered plus one dose vaccinated, COVID-19 recovered plus two doses vaccinated and breakthrough COVID-19 cases.
“The findings of the study demonstrated that the breakthrough cases and COVID-19 recovered individuals with one or two dose of vaccine had relatively higher protection against Delta variant in comparison to the participants who were administered either one or two doses of Covishield. “Prior vaccination results in less severe disease against subsequent infection provide evidence that both humoral and cellular immune response play an important role in protection,” the study added.