AstraZeneca found its antibody cocktail to be more than 80 percent effective at preventing symptomatic COVID-19 in a company analysis released on Thursday — a strong result for a treatment that could help immunocompromised people avert severe illness from COVID-19.

The pharmaceutical company said its study showed its long-acting antibody combination called AZD7442 reduced the risk of symptomatic COVID-19 by 83 percent over six months. The data has not yet been peer-reviewed but will be submitted for publication.

Researchers provided the one-time 300mg dose in two separate, sequential shots to participants, a majority of whom had comorbidities that put them at high risk of severe COVID-19.

Participants were not vaccinated, and researchers will continue to study them for 15 months.

Since about 2 percent of the world’s population is estimated to not have an adequate immune response to the COVID-19 vaccine, the preventative treatment would be designed to help these at-risk people prevent serious illness from the virus.

In a separate analysis of another trial, one 600mg dose of AstraZeneca’s long-acting antibody combination was found to reduce the risk of severe COVID-19 and death by 88 percent among patients who were treated within three days of developing symptoms.

In the works: AstraZeneca previously submitted a request to the Food and Drug Administration (FDA) to grant an emergency use authorization for AZD7442 last month.