The FTSE 100 pharma company said the jab was well tolerated, and the independent data safety monitoring board (DSMB) identified no safety concerns related to the vaccine.
The DSMB conducted a specific review of thrombotic events, as well as cerebral venous sinus thrombosis (CVST) with the assistance of an independent neurologist.
The DSMB found no increased risk of thrombosis or events characterised 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.
This interim analysis was based on 32,449 participants, 141 of which developed symptoms of COVID-19. The trial had a 2:1 randomisation of vaccine to placebo.
The inoculation was also 79% effective at preventing symptoms, with comparable results across ethnicity and age and 80% efficacy in participants aged 65 years and over.
The firm will continue to analyse the data and prepare for the primary analysis to be submitted to the US Food and Drug Administration for Emergency Use Authorisation in the coming weeks.
It will also be submitted for publication in a peer-reviewed journal.