AstraZeneca has reported that a single dose of its Covid-19 vaccine, Vaxzevria, was 82% effective against hospitalisation or mortality caused by the SARS-CoV-2 virus’ Beta or Gamma variants.
The data is from a study by the Canadian Immunization Research Network (CIRN) with support from the Public Health Agency of Canada and the Canadian Institutes of Health Research.
Co-created by the University of Oxford and Vaccitech, Vaxzevria utilises a weakened adenovirus and has the SARS-CoV-2 virus spike protein’s genetic material.
The study analysed the vaccine in a total of 69,533 Covid-19 patients in Ontario, Canada. Of these, 28,705 subjects tested positive for non-variants of concern and 40,828 were positive for a variant of concern of SARS-CoV-2.
Results showed that apart from the Beta/Gamma variants, the vaccine was highly effective against the Delta (B.617.2) and Alpha (B.1.1.7) variants by reducing hospitalisations or deaths by 87% and 90%, respectively.
Furthermore, the efficiency of the vaccine following one dose against hospitalisation or mortality was in line with that of other vaccines analysed in the study.
Against any symptomatic disease caused by Beta or Gamma variants, the vaccine was 50% effective while it was 70% and 72% effective against the Delta and Alpha variants, respectively.
Follow-up time was not adequate to report on the vaccine’s effectiveness after two doses but other studies demonstrated improved effectiveness with the indicated two-dose schedule, the company said.
A single dose of Vaxzevria was effective against milder symptomatic Covid-19 but the effectiveness was lower compared to the severe disease.
AstraZeneca BioPharmaceuticals R&D executive vice-president Mene Pangalos said: “With different variants threatening to disrupt our route out of the pandemic, this real-world evidence shows that Vaxzevria, along with other vaccines used in Canada, provides a high level of protection against the most serious forms of the disease, even after just one shot.
“It is essential that we continue to protect as many people as possible in all corners of the world in order to get ahead of this deadly virus.”
In a Phase I/II trial conducted by the University of Oxford and the University of the Witwatersrand in January, the vaccine demonstrated limited effectiveness against mild disease caused mainly by the Beta variant.
Last month, AstraZeneca started the inoculation of the first subjects in Phase II/III trial of its Covid-19 variant vaccine to prevent infection from variant SARS-CoV-2 strains.