Pre-exposure prophylaxis with a combination of two long-acting antibodies significantly reduced the occurrence of symptomatic disease in high-risk unvaccinated patients, as per the results from the phase III PROVENT trial.

The randomized, placebo-controlled PROVENT trial examined the safety and effectiveness of AZD7442, administered as intramuscular (IM) single dose of 300mg, in preventing COVID-19 compared to the placebo; 3460 received the study drug, while 1737 were given the placebo. AZD7442 is a combination product of two long-acting monoclonal antibodies LAABs - tixagevimab (AZD8895) and cilgavimab (AZD1061) - derived from B-cells donated by convalescent patients after SARS-CoV-2 virus.

The study participants had not been vaccinated when they were recruited for the study and had tested negative for the SARS-CoV-2 on serology testing. The trial was conducted in multiple countries such as the US, UK, Spain, France and Belgium.

More than three-quarters of the study group had a comorbid condition (such as diabetes, severe obesity, heart disease, COPD, chronic kidney disease, and chronic liver disease). These conditions are associated with decreased or impaired immune response to the vaccine. The participants also included older adults (≥60 years) and those who were taking immunosuppressive medications or had an immunosuppressive disease. The primary outcome measure was the first RT PCR confirmed symptomatic case occurring up to day 183 (6 months). The follow up period is 15 months.

The study found that AZD7442 reduced the risk of developing symptomatic COVID-19 by 77%. Compared to placebo group, no patient developed severe COVID-19 and no deaths occurred in the intervention group. Moreover, the treatment was also well-tolerated.

This trial has shown that one dose of AZD7442, delivered in a convenient intramuscular form, can quickly and effectively prevent symptomatic COVID-19. It offers an option for those individuals who do not develop adequate antibodies with the vaccine and hence may not be adequately protected despite vaccination. Together with the vaccine, the long-acting antibody combination prevent risk of developing symptomatic infection.

(Source: MedPage Today August 20, 2021)