FDA delays decision on Moderna's RSV shot until the end of May

What difference does a few weeks make? 

Moderna will have to consider that after receiving word that the FDA will not meet a May 12 decision date for its respiratory syncytial virus (RSV) vaccine candidate. The vaccine maker said Friday that it was recently notified by the agency that, due to “administrative constraints,” a decision on mRNA-1345 has been pushed until the end of the month. 

The FDA has not raised any issues with the vaccine that could prevent approval, the company said, and all systems remain go for June’s Advisory Committee on Immunization Practices meeting to discuss RSV vaccination. 

“We look forward to helping the agency complete the review of our application, and to the June ACIP meeting,” Moderna President Stephen Hoge, M.D., said in a release. 

Investors at William Blair were undeterred, writing in a note that the administrative reasoning indicates the vaccine will likely still be approved during the biologics license application review cycle. Most importantly, an end of May decision would still allow Moderna to be included in the ACIP’s end of June meeting where immunization recommendations are made. 

Larger investor sentiment seemed to roughly mirror that of William Blair’s, with Moderna’s share price down 2.7%, from $122.69 to $119.38 on Friday morning. 

Moderna is seeking to be the third entrant into the $10 billion adult RSV vaccine market behind GSK and Pfizer, though the candidate doesn’t quite have the same blockbuster data that catapulted the biotech's COVID shot in the pandemic years. Of most concern is the RSV shot’s durability, after Moderna reported earlier this year that the efficacy dropped 20 percentage points between the three-month mark post-vaccination to nine months. GSK’s Arexvy had a 67.2% average efficacy across two seasons, and Pfizer’s Abrysvo had 65.1% efficacy in the first year, which dropped to 55.7% in the second season. 

Where Moderna hopes to have an edge is on administration, touting its prefilled syringe as a significant advantage over the first entrants. If it’s easier for pharmacists to use, than they will choose it more, is the hopeful thinking among executives. CEO Stephane Bancel said on the company’s recent first-quarter earnings call that his team was working with pharmacists “literally on a daily basis.” 

Editor's note: This story was updated with more recent Abrysvo data from February 2024.