AstraZeneca, which announced the latest data from Phase III trials of its new Covid-19 drug — AZD7442 — said both the prevention and outpatient treatment studies showed robust efficacy from a one-time intramuscular (IM) dose of the long-acting antibody combination.

The ongoing ‘PROVENT’ trial evaluating a median six months of participant follow-up, one 300mg IM dose of AZD7442 reduced the risk of developing symptomatic COVID-19 compared to placebo by 83 percent, the company said. More than 75 percent of PROVENT participants at baseline had comorbidities that put them at high risk for severe COVID-19 if they were to become infected, including people who are immunocompromised and may have a reduced immune response to vaccination. There were no cases of severe COVID-19 or COVID-19-related deaths in those treated with AZD7442 at either the primary or six-month analyses. In the placebo arm, there were two additional cases of severe COVID-19 at the six-month assessment, for a total of five cases of severe COVID-19 and two COVID-related deaths. An exploratory analysis of the ‘TACKLE’ outpatient treatment trial, in patients with mild-to-moderate COVID-19, showed that one 600mg IM dose of AZD7442 reduced the risk of developing severe COVID-19 or death (from any cause) by 88 percent compared to placebo in patients who had been symptomatic for three days or less at the time of treatment. A total of 90 percent of participants enrolled in TACKLE were from populations at high risk of progression to severe COVID-19 if they became infected, including those with comorbidities, AstraZeneca said in a statement.

The AZD7442 PROVENT trial was the first Phase III trial prospectively designed to evaluate a monoclonal antibody for pre-exposure prophylaxis of symptomatic COVID-19, with targeted inclusion of high-risk and immunocompromised participants.