A study by Lancet has indicated that the Covishield vaccine was effective against moderate-to-severe COVID-19 even as India faced a deadly second wave, spurred by the Delta variant.?
The Serum Institute manufactured jab is one of three vaccines that have been used to administer more than 1.2 billion jabs to India's adult population.?
As per data available with the Serum Institute, the overall efficacy against symptomatic COVID-19 after more than 14 days after the 2nd dose is 66.7 per cent.
The study found that the vaccine effectiveness against the Covid infection in fully vaccinated individuals was 63 per cent. More importantly, the efficacy was higher at 81 per cent against moderate-to-severe disease.
The scientists also observed that the spike-specific T-cell responses were conserved against both the Delta variant and wild-type virus.
"Such cellular immune protection might compensate for waning humoral immunity against the virus variants and prevent moderate-to-severe disease and need for hospitalisation. This study provides comprehensive data on the real-world vaccine effectiveness and immunological response to vaccination which should help guide policy," the study noted.
The study was conducted at two medical research centres in Faridabad, between April 1 and May 31 this year.?
The two-dose Covishield regime however provides modest protection against the Delta variant of COVID-19 and higher levels of protection against moderate-to-severe COVID-19 .
The findings come even as a new Covid variant - Omicron or the B.1.1.529 was detected in South Africa last week and designated by the World Health Organisation (WHO) as a ''variant of concern'' - has set off alarm bells across the world.
On Monday, the WHO said the Omicron variant poses a "very high" risk globally, stressing that uncertainties remained about how contagious and dangerous the strain was.?
Detected a little more than a week ago in South Africa, it has since spread to 16 countries. It is not yet known whether existing COVID-19 vaccines will be effective against this new strain.
Covishield-maker Serum Institute of India has resumed vaccine exports for distribution to low- and middle-income nations under the global vaccine-sharing programme COVAX.