FDA delays decision on Moderna’s RSV vaccine

Moderna’s first attempt to expand its commercial activities beyond COVID-19 vaccines, its respiratory syncytial virus (RSV) shot, has suffered a delay in the US.

The company said the FDA would not be able to complete its review of the mRNA-1345 vaccine by the scheduled date of 12th May due to “administrative constraints”, causing nervousness among investors that led to a near-3% decline in its share price.

The fear for shareholders is that a delay could mean that mRNA-1345 won’t be ready to roll out in the US in time for the forthcoming RSV season, which starts in the autumn, although, Moderna said in a statement that the FDA has said it hopes to complete the review by the end of this month.

mRNA-1345 is playing catch-up in the emerging RSV vaccine category with GSK’s Arexvy and Pfizer’s Abrysvo, which are both conventional protein-based vaccines and launched in time for the 2023-24 RSV season.

GSK seems to have won the initial rollout contest, with sales of £1.2 billion ($1.5 billion) by the end of 2023, compared to $515 million for the Pfizer shot. First-quarter 2024 sales came in a £182 million and $145 million, respectively.

Moderna said the FDA has indicated that it doesn't have any issues related to vaccine safety, efficacy, or quality that would prevent the approval of mRNA-1345, adding that the vaccine remains on track to be reviewed at the Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunisation Practices (ACIP) meeting 26th to 27th June. ACIP approval is also required for a commercial launch to go ahead.

Moderna’s application is based mainly on phase 3 data that showed it had 83.7% efficacy in preventing RSV lower respiratory tract disease (RSV-LRTD) in older adults aged 60 and over. It has been developed at breakneck speed, only starting clinical testing in 2021, and is a key part of Moderna’s efforts to counteract a sharp reduction in COVID-19 vaccine sales.

The delay may not be much of a setback, as RSV is a very big pie to share, given the massive size of the older adult population. There are millions of cases recorded annually, with around 360,000 hospitalisations and more than 24,000 deaths worldwide each year.

“Moderna is very grateful to the FDA for their continued efforts and diligence” said Stephen Hoge, the company’s president. “We look forward to helping the agency complete the review of our application, and to the June ACIP meeting.”

The company is also working on influenza, combined flu/COVID, flu/COVID/RSV, and cancer vaccines as it tries to diversify its business.