Moderna launches Phase 3 trial for mRNA RSV vaccine candidate

Following an endorsement from the independent Data and Safety Monitoring Board this week, Moderna, Inc. officially began the third phase of trials for its mRNA Respiratory Syncytial Virus (RSC) vaccine candidate this week.

The safety greenlight was based on preliminary Phase 2 safety and tolerability data of mRNA-1345, which studied its effects on adults 60 years old and older. That data found the vaccine’s safety profile acceptable, supporting its wider application among approximately 34,000 participants across multiple countries for Phase 3.

RSV is a common respiratory virus that usually manifests with cold-like symptoms. Recovery takes for most between one to two weeks, but among the young and old especially, its effects can be more severe, causing pneumonia and respiratory distress. Approximately 177,000 people are hospitalized each year in the United States due to the virus, and about 14,000 adults older than 65 die.

“RSV is one of the most widespread respiratory viruses, causing severe disease and hospitalization in older adults, and yet there is no vaccine available on the market,” Stéphane Bancel, CEO of Moderna, said. “We believe that our vaccine candidate against RSV has the potential to protect against over 1 million infections globally each year, improving quality of life for those at high-risk of becoming infected and reducing the burden on health care systems. An mRNA vaccine against RSV could have a positive impact on individuals, communities, and global public health. Our ultimate goal is to combine our RSV vaccine with our COVID-19 and flu boosters into a single-dose booster.”

RSV, like flu, tends to be seasonal, striking primarily in fall, winter, and spring. The introduction of COVID-19 appears to have changed up those normal transmission patterns, however, leading to unusual levels of infection and a special health alert from the Centers for Disease Control and Prevention (CDC) – an especially concerning state of events, given that no approved vaccine for RSV currently exists.

Phase 3 of Moderna’s study will focus on mRNA-1345’s safety and efficacy in adults at least 60 years old, with eventual licensure of the vaccine as an end goal. At the same time, preclinical studies have shown that its seasonal flu, RSV, and COVID-19 booster vaccines could be combined into a single dose and produce immune responses to all six antigens, prompting further examination.