AstraZeneca's monoclonal antibody combination tixagevimab-cilgavimab (Evusheld) reduced the risk of symptomatic COVID-19 infection by 83% over placebo at a median follow-up of 6 months, finds a phase 3 randomized clinical trial published yesterday in the New England Journal of Medicine.

As part of an ongoing trial, US and European PROVENT Study Group members, which included AstraZeneca representatives, enrolled 5,197 COVID-naïve adults at elevated risk for inadequate immune response to COVID-19 vaccination and/or exposure to SARS-CoV-2 at 87 sites from Nov 21, 2020, to Mar 22, 2021, before the rise of the Delta and Omicron variants.

The researchers randomly assigned participants in a 2:1 ratio to receive one intramuscular 300-milligram dose of either Evusheld (3,460) or a saline placebo (1,737) and contacted them weekly about any COVID-19 symptoms for up to 183 days.