the staff of the Ridgewood blog
Ridgewood NJ, according to Johns Hopkins Center for Health Security, AstraZeneca announced preliminary results from a Phase 3 clinical trial for its SARS-CoV-2 vaccine, developed in collaboration with the University of Oxford. The trial included more than 32,000 participants in Chile, Peru, and the US, including 21,583 who received at least one dose of the vaccine. The press release reports an overall efficacy of 79% against any COVID-19 disease among all age groups and 80% efficacy for adults aged 65 years and older. Additionally, the press release describes 100% efficacy against severe disease and hospitalization. AstraZeneca explicitly noted that an independent review of the safety data “found no increased risk of thrombosis or events characterized by thrombosis” associated with the vaccine. Previous analysis of data from trials in Brazil, South Africa, and the UK estimated the overall efficacy to be 60%.
AstraZeneca has not yet published the full clinical trial data—including the number of severe cases and hospitalizations among the placebo group nor data pertaining to emerging variants—and the results have not yet been subjected to peer review. The press release indicates AstraZeneca is continuing to analyze the trial data to prepare a final analysis for submission to the US FDA. The AstraZeneca-Oxford vaccine has received a conditional marketing authorization in the EU and similar emergency use authorizations in a number of other countries as well as an emergency use listing from the WHO, but it has not been granted an Emergency Use Authorization from the US FDA. Similar to the J&J-Janssen vaccine, the AstraZeneca-Oxford vaccine does not require freezer (or ultra-cold freezer) temperatures for storage and transportation, which reduces logistical and operational barriers to mass vaccination efforts.
The US National Institute of Allergy and Infectious Diseases (NIAID) issued a statement that called into question the vaccine’s efficacy estimate. The statement indicated the Data Safety Monitoring Board (DSMB) that oversaw the clinical trials had concerns regarding the efficacy reported in the press release. In particular, the DSMB expressed concern that “outdated information” was included in the calculation, “which may have provided an incomplete view of the efficacy data.” No further details were provided, but the NIAID called on AstraZeneca to work with the DSMB to identify and correct any issues. In response, AstraZeneca stated the preliminary results were based on a “pre-specified interim analysis” of a subset of data collected through February 17. AstraZeneca indicated that it is validating its statistical analysis and engaging with the DSMB, with the goal of publishing the primary results in the next 48 hours.