AZD 1222 US phase III trial met primary efficacy endpoint in preventing COVID-19 at interim analysis – AstraZeneca

The AstraZeneca US Phase III trial of AZD 1222 demonstrated statistically significant vaccine efficacy of 79% at preventing symptomatic COVID-19 and 100% efficacy at preventing severe disease and hospitalisation. This interim safety and efficacy analysis was based on 32,449 participants accruing 141 symptomatic cases of COVID-19.

The trial had a 2:1 randomisation of vaccine to placebo. Vaccine efficacy was consistent across ethnicity and age. Notably, in participants aged 65 years and over, vaccine efficacy was 80%.
The vaccine 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.