AstraZeneca (AZ) and Oxford University’s COVID-19 vaccine has hit its primary endpoint in a phase 3 trial conducted in the US.
In an interim analysis, the vaccine – also known as AZD1222 – demonstrated a vaccine efficacy of 79% at preventing symptomatic COVID-19, as well as 100% efficacy at preventing severe disease and hospitalisation.
The researchers also reported that the vaccine efficacy was consistent across ethnicity and age, with participants aged 65 years and over demonstrating a vaccine efficacy of 80%.
In addition, the independent data safety monitoring board (DSMB) identified no safety concerns related to the vaccine.
This included a specific review of thrombotic events, as well as cerebral venous sinus thrombosis (CVST) with the assistance of an independent neurologist.
Following this review, the DSMB found no increased risk of thrombosis or events characterised by thrombosis among the 21,583 participants who had received at least one dose of the vaccine, with no specific CVST events found in this trial.
This announcement follows the conclusion of a review from the European Medicines Agency (EMA) that found the AZ/Oxford vaccine is not associated with an increase in the overall risk of blood clots, also referred to as thromboembolic events.
The EMA review was conducted after a small number of reports of blood clots in people who had received the AZ/Oxford vaccine.
AZ said in a statement that it will continue to analyse the data and prepare for the primary analysis to be submitted to the US Food and Drug Administration (FDA) for an emergency use authorisation (EUA) ‘in the coming weeks’.
“These results add to the growing body of evidence that shows this vaccine is well tolerated and highly effective against all severities of COVID-19 and across all age groups,” said Mene Pangalos, executive vice president, BioPharmaceuticals R&D, AZ.
“We are confident this vaccine can play an important role in protecting millions of people worldwide against this lethal virus. We are preparing to submit these findings to the US Food and Drug Administration and for the rollout of millions of doses across America, should the vaccine be granted US emergency use authorisation,” he added.
Although the US trial administered two doses of AZD1222 at a four-week interval, previous trials have shown that an extended interval of up to 12 weeks demonstrated increased efficacy.
Based on the extended dosing evidence, administration of the second dose at an interval longer than four weeks may further increase efficacy, according to AZ.