Phase 3 Data Demonstrate RSVpreF Vaccine Efficacy in Older Adults with RSV

The phase 3 clinical trial RENOIR (RSV vaccine efficacy study in older adults immunized against RSV disease) provided positive top-line data supporting Pfizer’s bivalent respiratory syncytial virus (RSV) prefusion F vaccine candidate, RSVpreF. The study investigated the efficacy, immunogenicity, and safety of a single vaccine dose in adults 60 years of age and older.

The primary endpoint of the global, randomized, double-blind, placebo-controlled study was lower respiratory tract illness (LRTI-RSV). Investigators defined this by analysis of 3 or more respiratory syncytial virus-associated symptoms.

They observed an 85.7% efficacy rate in patients who experienced severe disease manifestation. The vaccine was well-tolerated with no new safety concerns to note.

“We are delighted that this first bivalent RSV vaccine candidate, RSVpreF, was observed to be efficacious in our clinical trial against this disease, which is associated with high levels of morbidity and mortality in older adults,” Annaliesa Anderson, PhD, Senior Vice President and Chief Scientific Officer, Vaccine Research and Development, Pfizer, said in a statement.

Respiratory syncytial virus disease can cause serious illness even among healthy individuals. It’s characterized by a varying range of respiratory symptoms affecting the lungs and breathing passages. Outcomes in older adults who contract this virus have the potential to be fatal, especially with certain coexisting conditions.

Global estimates report that 336,000 older adults are hospitalized each year due to RSV. The US sees approximately 177,000 hospitalizations and 14,000 deaths in this population. Currently, supportive care is the standard as there are no prophylactic or therapeutic options.

“Scientists and researchers have worked to develop RSV vaccines with little success for over half a century,” Anderson explained. “These findings are an important step in our effort to help protect against RSV disease, and we look forward to working with the FDA and other regulatory agencies to make this vaccine candidate available to help address the substantial burden of RSV disease in older adults."

According to the announcement, Pfizer plans to submit for regulatory approval in Fall 2022 based on the results from this interim efficacy analysis. The company is also aiming to present these data at a future medical congress and to seek peer-reviewed publication in a scientific journal.