AstraZeneca posts U.S. vax trial data

March 22, 2021

AstraZeneca said that results from its U.S. phase 3 trial of AZD1222 — its COVID-19 vaccine co-invented with the University of Oxford — demonstrate statistically significant vaccine efficacy as well as a favorable safety profile.

According to the drugmaker, trial data suggests a vaccine efficacy of 79% at preventing symptomatic COVID-19 and 100% efficacy at preventing severe disease and hospitalization. The trial included two doses administered at a four week interval.

Vaccine efficacy was consistent across ethnicity and age. Notably, in participants aged 65 years and over, vaccine efficacy was 80%.

This comes on the heels of declining vaccine confidence, after reports of blood clots caused countries across Europe to halt distribution, with the most recent scare coming out of Denmark this weekend, where two people reportedly suffered brain hemorrhages after receiving the vaccine. The EMA, however, has concluded that the vaccine remains “safe and effective,” but could not rule out a link to the small number of blood clot cases.

During the U.S. trial, AstraZeneca's 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 with 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.

AstraZeneca said it will seek emergency use authorization from the U.S. FDA “in the coming weeks." An FDA  vaccine advisory committee will publicly debate the evidence behind the shots before the agency decides whether to allow emergency use. AstraZeneca says that if given the FDA nod, the company can deliver 30 million doses immediately — and another 20 million within the first month.

Read the AZ press release