An Indian Council of Medical Research (ICMR) study conducted in Chennai has found that the Delta variant of the Covid-19 virus has the potential to infect both vaccinated and unvaccinated people, but it reduces mortality among the former group.

The study findings indicate that the prevalence of B.1.617.2 was not different between the vaccinated and unvaccinated groups. Delta variant was the dominant circulating strain and one of the primary drivers for the second wave of SARS-CoV-2 in India.

Those involved in the study include researchers from the National Institute of Epidemiology. The study was conducted on COVID-infected persons, both vaccinated and unvaccinated ones, in the Greater Chennai Corporation's triage centers between May 3 and 7.

"Studies have documented reduction in neutralization titers among Covishield and Covaxin recipients after infection with Delta variant. This might be the reason for the breakthrough infections observed in the fully vaccinated individuals," the ICMR study said.

The pace and scale of vaccination have to be increased to mitigate the further waves of the pandemic. Systematic genomic surveillance must be carried out to monitor the emergence of newer variants and assess their capacity to evade infection/vaccine-induced immunity, it added.

In another study, according to a Reuters report, the efficacy of the Pfizer or the AstraZeneca vaccine in preventing infections slipped to 75% and 61% respectively, 90 days after a second shot of the vaccines -- down from 85% and 68%, respectively, seen two weeks after the second dose.

In this British public health study, they also highlighted the increased risk of contagion from the Delta variant even as the study showed that those who do get infected despite being fully vaccinated tend to have a viral load similar to the unvaccinated with an infection.