US trial data shows Oxford-AstraZeneca vaccine is ‘safe and highly effective’

By Jane Byrne

- Last updated on GMT

© GettyImages/insta_photos
© GettyImages/insta_photos

Related tags COVID-19 Phase 3 thrombosis Astrazeneca

The Oxford-AstraZeneca vaccine was 79% effective in preventing symptomatic COVID-19, according to the findings of the Phase 3 study in the US, Chile and Peru, says AstraZeneca.

The company will now use the data to apply to the US Food and Drug Administration (FDA) for emergency use authorization for the vaccine in that country “in the coming weeks.”

AstraZeneca COVID-19 vaccine was also 100% effective against severe or critical disease and hospitalization, said the pharma giant.

This AstraZeneca-led US Phase III trial included two doses administered at a four-week interval. It comprised over 32,000 volunteers across all age groups, relying on 88 trial centers in the US, Peru, and Chile.

The results of the study, which adds to previous trial data from the UK, Brazil and South Africa, as well as real-world impact data from the UK, may provide additional evidence of the vaccine’s efficacy in the elderly after some EU countries decided against using the shot in their vaccination programs for those older than 65; AstraZeneca reported that there was 80% efficacy in participants aged 65 years and over, with comparable efficacy across ethnicity and age.

The pharma group said the trial results also demonstrated that the vaccine was well tolerated. “An independent data safety monitoring board (DSMB) identified no safety concerns related to the vaccine.”

Those reviewers particularly looked at the risk of thrombotic events, as well as cerebral venous sinus thrombosis (CVST), in participants, using the assistance of an independent neurologist. “The DSMB found no increased risk of thrombosis or events characterized by thrombosis among the 21,583 participants receiving at least one dose of the vaccine. The specific search for CVST found no events in this trial.”

Again, those findings could further reassure some European countries that recently suspended the rollout of the vaccine over concerns about a possible link to blood clots. The EU regulatory body, the European Medicine Agency (EMA), though, also determined that the vaccine is “safe and effective” ​in its recent review. 

The trial cohort

Amongst participants in the interim analysis, about 79% were white/Caucasian, 8% black/African American, 4% native American and 4% Asian, and 22% of participants were Hispanic.

Approximately 20% of participants were 65 years and over, and approximately 60% had co-morbidities associated with an increased risk for progression of severe COVID-19, such as diabetes, severe obesity, or cardiac disease.

‘Validation’ of the vaccine

Ann Falsey, professor of medicine, University of Rochester School of Medicine, US, and co-lead principal investigator for the trial, said: “These findings reconfirm previous results observed in AZD1222 trials across all adult populations but it’s exciting to see similar efficacy results in people over 65 for the first time. This analysis validates the AstraZeneca COVID-19 vaccine as a much-needed additional vaccination option, offering confidence that adults of all ages can benefit from protection against the virus.”

Andrew Pollard, professor of pediatric infection and immunity, and lead investigator of the Oxford University trial of the vaccine, said the results show the remarkable efficacy of the vaccine in a new population and are consistent with the results from Oxford-led trials. “We can expect strong impact against COVID-19 across all ages and for people of all different backgrounds from widespread use of the vaccine.’ 

Sarah Gilbert, professor of vaccinology, the University of Oxford, and co-designer of the vaccine, said the new results provide further confirmation of the safety and effectiveness of the shot. “In many different countries and across age groups, the vaccine is providing a high level of protection against COVID-19 and we hope this will lead to even more widespread use of the vaccine in the global attempts to bring the pandemic to an end.”

AstraZeneca will be submitting the data for analysis by the scientific community in peer-review literature, as well as seeking an EUA from the US FDA. 

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