Just months after the announcement that Pfizer, and later GSK, had demonstrated strong results in trials for their RSV vaccine candidates, Moderna released a statement in January 2023 indicating that the mRNA vaccine candidate mRNA-1345 had met primary efficacy endpoints. The statement suggests that the ConquerRSV Phase III trial explored the efficacy of the investigational vaccine in older adults. Moderna anticipates submitting for regulatory approval in “the first half of 2023”. 


Professor Abdullah Baqui, a principal investigator for the study sites in Bangladesh, described the danger of RSV to “older and high-risk adults, particularly those with comorbidities”. The trial, a randomised, double-blind, placebo-controlled study, enrolled approximately 37,000 adults over the age of 60. It spans 22 countries.  

The primary efficacy endpoints were based on two definitions of RSV-LRTD defined as “ether two or more symptoms, or three or more symptoms of disease”. The trial continues with “additional efficacy analyses planned”.   

An independent Data and Safety Monitoring Board (DSMB) reviewed available safety data. “No safety concerns” were identified but safety and tolerability will “continue to be followed”. The primary efficacy endpoints were met, including VE of 83.7% against RSV_LRTD as defined by two or more symptoms.  

More mRNA for Moderna 

CEO Stéphane Bancel described the results as an “important step forward” in tackling RSV in adults over 60. The “encouraging” data comprise the “second demonstration of positive Phase III trial results from [Moderna’s] mRNA infectious disease vaccine platform”. He looks forward to sharing the results in more detail at a conference.  

“Respiratory diseases are a major public health priority given they have a significant health impact”. 

Thus, Moderna is “committed to developing a portfolio of respiratory mRNA vaccines to target the most significant viruses causing respiratory disease”. 

For more on the race to RSV vaccines at the World Vaccine Congress in Washington in April, get your tickets at this link.