Delta variant infects both vaccinated, unvaccinated: ICMR study

Findings from an Indian Council of Medical Research (ICMR) study conducted in Chennai have shown that the Delta variant of the coronavirus has the potential to infect both unvaccinated and vaccinated individuals, but it reduces mortality among the latter group.

The Institutional Ethics Committee of ICMR-National Institute of Epidemiology, Chennai had approved this study and it was published in the Journal of Infection on August 17. According to the study findings, the prevalence of the B.1.617.2 variant "was not different between the vaccinated and unvaccinated groups."

B.1.617.2, or the Delta variant SARS-CoV-2, the virus which causes COVID-19 infection, was the dominant circulating strain and one of the primary drivers of the second wave of infections in India.

"B.1.617.2 has the potential to infect both vaccinated and un-vaccinated individuals. However, the progression of illness seems to be prevented by vaccination. Therefore, non-pharmaceutical interventions must continue to slow down the transmission. Additionally, the pace and scale of vaccination have to be increased to mitigate the further waves of the pandemic," the report based on the study read, according to ANI.

"Systematic genomic surveillance must be carried out to monitor the emergence of newer variants and assess their capacity to evade infection/vaccine-induced immunity," the report added.

The report has quoted other studies which had shown a reduction in neutralisation among Covaxin and Covishield vaccine beneficiaries following infection with the Delta variant of the virus.

"Studies have documented reduction in neutralization titres 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 report mentioned.

The report adds that the proportion of patients progressing to severe illness and mortality was lower in individuals who were vaccinated against COVID-19. "No deaths were reported in the fully vaccinated group, whereas three partially vaccinated (patients) and seven unvaccinated patients died," the report said.

The study had included COVID-19 patients who had visited Greater Chennai Corporation's triage centers between May 3 and 7. Out of the 3,790 COVID-19 patients who visited the triage centres during this time, 371 had received at least a single dose of the COVID-19 vaccine. The study enrolled 354 out of the 371 vaccinated individuals. Out of the 3,417 unvaccinated people, 185 were enrolled for the study. Out of the 354 vaccinated individuals, 241 had taken a single dose of the vaccine and 113 had taken two doses.

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