COVID-19: Who are highly protected against Delta variant? ICMR reveals

New Delhi: A new study conducted by the Indian Council of Medical Research (ICMR) has found that individuals who have recovered from COVID-19 and have received one or both doses of vaccine exhibit relatively higher protection against Delta variant in comparison to those administered either one or two doses of Covishield. 

According to the study, the humoral and cellular immune response plays a vital role in protection against the Delta variant of COVID-19, which is more transmissible and virulent than other mutated strains.

The study, which is yet to be peer-reviewed, posted on the bioRxiv preprint server on Friday (July 2, 2021) is named 'Neutralisation of Delta Variant with Sera of Covishield vaccines and COVID-19 Recovered Vaccinated Individuals' was 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 recent emergence of B.1.617 lineage has created grave public health problems 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 high transmissibility associated with Delta variant led to the second wave of the pandemic in India which affected millions of people. Besides this, a 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.

The study also stated that only limited information is available on the duration of protective immune response post-infection, vaccination or breakthrough infection with SARS-CoV-2.

It evaluated the immune response of individuals immunized with Covishield (first dose and second dose), COVID-19 recovered people who have received one dose of vaccination, COVID-19 recovered people who have received both doses of vaccination 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,” the study said.

"Prior vaccination results in less severe disease against subsequent infection provide evidence that both humoral and cellular immune response plays an important role in protection," the study added.