AstraZeneca reports reduced efficacy of 76% in U.S. Phase III Covid trial

AstraZeneca said “positive high-level results” from the primary analysis of the Phase III trial of AZD1222 in the U.S. have confirmed vaccine efficacy consistent with the pre-specified interim analysis announced on March 22. The results have been presented to the independent Data Safety Monitoring Board. The primary analysis is pre-specified in the protocol and will be the basis for a regulatory submission for Emergency Use Authorization to the Food and Drug Administration in the coming weeks, AstraZeneca said. The primary efficacy analysis included the accrual of 190 symptomatic cases of COVID-19 from the 32,449 trial participants, an additional 49 cases to the previously announced interim analysis. Participants were randomized on a 2:1 ratio between the vaccine and placebo group. The primary endpoint, vaccine efficacy at preventing symptomatic COVID-19 was 76%, occurring 15 days or more after receiving two doses given four weeks apart. On Monday, Astra reported efficacy of 79%. A key secondary endpoint, preventing severe or critical disease and hospitalization, demonstrated 100% efficacy. There were eight cases of severe COVID-19 observed in the primary analysis with all of those cases in the placebo group, the company noted. The vaccine was well tolerated, and no safety concerns related to the vaccine were identified, it added. There were 190 cases in the primary analysis. There are 14 additional possible or probable cases to be adjudicated so the total number of cases and the point estimate may fluctuate slightly. AstraZeneca will also submit the primary analysis for peer-reviewed publication in the coming weeks.