Real-world data from Canada showed 82% and 87% effectiveness after one dose against hospitalization or death caused by Beta/Gamma and Delta variants respectively.
Results from the Canadian Immunization Research Network (CIRN) with support from Public Health Agency of Canada and the Canadian Institutes of Health Research, published as a pre-print, demonstrated one dose of Vaxzevria was 82% effective against hospitalisation or death caused by the Beta/Gamma variants of the SARS-CoV-2 virus, states AstraZeneca in a press release.
The effectiveness of Vaxzevria after one dose against hospitalisation or death was similar to that of other vaccines tested in the study. Follow-up time was not sufficient to report on effectiveness of Vaxzevria after two doses, other studies have shown an increased effectiveness following the indicated two dose schedule, the company states.
Vaxzevria was effective against milder symptomatic disease although, given that data was only reported after a first dose instead of the indicated two dose schedule where efficacy is known to be enhanced in this disease setting, the efficacy was lower than against severe disease. Vaccine effectiveness against any symptomatic disease was 50% against the Beta/Gamma variants, and 70% and 72% against the Delta and Alpha variants, respectively.
The analysis included 69,533 individuals who tested positive for SARS-CoV-2 during December 2020 to May 2021 in Ontario, Canada; with 28,705 (6.8%) positive for non-variants of concern SARS-CoV-2 and 40,828 (9.7%) positive for a variant of concern.
Photo: AstraZeneca R&D