However, there is limited information available on the duration of protective immune response post-infection, vaccination or breakthrough infection with SARS-CoV-2.
Amid rising concerns about the spread of the Delta Covid variant in India, a new study has found that those who have already been infected with the virus and have received even one dose of the Covid-19 vaccine, have a relatively higher protection against the new variant as compared to those who have been vaccinated with Covishield.
The yet to be peer-reviewed study further stated that there’s evidence to suggest that both humoral and cellular immune response play an important role in protecting one from the virus.
The study which was posted on bioRxiv preprint server on Friday, was carried out 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.
It's titled, 'Neutralisation of Delta Variant with Sera of Covishield vaccines and Covid-19 Recovered Vaccinated Individuals'.
This development comes in the backdrop of India logging 43,071 new coronavirus cases and 955 fatalities on Saturday. According to the Union health ministry data updated at 8 am today, more than 52,000 patients recovered from the disease in last 24 hours taking total recoveries to over 2.96 crore.
While infections have been steadily declining, 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 variant of concern,” the new study stated.
"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 have been reported to show lower neutralisation to several approved vaccines. This has led to breakthrough infections after completion of vaccination regimen," it said.
There is limited information available on the duration of protective immune response post-infection, vaccination or breakthrough infection with SARS-CoV-2.
The study evaluated immune response in sera 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.
(With PTI inputs)