AstraZeneca has published the primary analysis results from the Phase III clinical trials of its Covid-19 vaccine in the UK, Brazil and South Africa, which showed that the vaccine is safe and effective in preventing Covid-19 more than 22 days after the first dose.

Co-invented by the University of Oxford and Vaccitech, the vaccine uses a replication-deficient chimpanzee viral vector based on an adenovirus and has the genetic material of the SARS-CoV-2 spike protein.

The primary efficacy analysis was based on 17,177 subjects accruing 332 symptomatic cases from the Phase III UK (COV002), Brazil (COV003) and South Africa (COV005) trials.

These trials were led by Oxford University and AstraZeneca.

According to the results, vaccine efficacy was 76% after the first dose, with protection maintained to the second dose. When inter-dose interval was 12 weeks or more, vaccine efficacy increased to 82%.

Furthermore, the analysis demonstrated the vaccine’s potential in reducing asymptomatic transmission of the virus, based on weekly swabs obtained from volunteers in the UK trial.

PCR positive readings decreased by 67% after a single dose and 50% after two doses, the data showed, which supports substantial impact on viral transmission.

AstraZeneca BioPharmaceuticals R&D executive vice-president Mene Pangalos said: “This primary analysis reconfirms that our vaccine prevents severe disease and keeps people out of the hospital.

“In addition, extending the dosing interval not only boosts the vaccine’s efficacy but also enables more people to be vaccinated upfront.”

Meanwhile, the company collaborated with Matrix Medical Network to accelerate a clinical trial in the US for its long-acting monoclonal antibody (LAAB) combination, AZD7442, for the potential Covid-19 prevention.

Matrix will provide mobile health clinics and expert clinicians to reach increased risk and hard to recruit populations in AstraZeneca’s Phase III STORM CHASER trial in the US.

Last month, Care Access Research collaborated with AstraZeneca to speed up the Phase III STORM CHASER clinical trial in the US assessing AZD7442 for preventing Covid-19.