Covishield 63% effective against Covid, 81% against moderate-severe infection: Study
Vaccine effectiveness of Covishield against SARS-CoV-2 infection in fully vaccinated individuals was found to be 63% even as it offered 81% protection from moderate-to-severe disease, according to a new study published in The Lancet Infectious Diseases journal.
The scientists also observed that the spike-specific T-cell responses were conserved against both the Delta variant and wild-type SARS-CoV-2.
“Such cellular immune protection might compensate for waning humoral immunity against the virus variants and prevent moderate-to-severe disease and need for hospitalisation,” according to a statement by the Science and Technology ministry.
This study includes a comparison between 2,379 cases of confirmed SARS-CoV2 infection and 1,981 controls. Researchers conducted the study at two medical research centres in Faridabad. Of the confirmed infection cases, 85 (3.6%) were from the fully vaccinated group compared with 168 (8.5%) from the control group.
This study provides comprehensive data on the real-world vaccine effectiveness and immunological response to vaccination which should help guide policy, the statement from the ministry added.
A multi-institutional team of Indian researchers led by Translational Health Science and Technology Institute (THSTI) evaluated the real-world vaccine effectiveness of Covishield during the SARS-CoV-2 infection surge between April and May, 2021 in India.
They also assessed neutralising activity and cellular immune responses against the variants in healthy, vaccinated persons to understand the mechanisms of protection.
Studies from England and Scotland have reported effectiveness of 60 to 67% for the vaccine against infection by the Delta variant. Breakthrough infections due to the Delta variant have been reported after vaccination with mRNA vaccines, researchers said.