Moderna's mRESVIA Faces Challenges in RSV Vaccine Market

Moderna's mRESVIA respiratory syncytial virus vaccine has encountered difficulties competing in the 2026 market, according to a Seeking Alpha report. Pfizer and GSK, which reached the market earlier, established positions through supply chain arrangements and existing contracts that limited later entrants' access.

Recent data showed that protection from mRNA vaccines such as mRESVIA may decrease more quickly than from traditional subunit vaccines. This difference in duration of protection has affected uptake among healthcare providers and patients. The change reduced the overall addressable market from initial expectations of broad adult use.

The report stated that distribution networks and established relationships have become central factors in RSV vaccine sales. Moderna's product achieved lower-than-expected results in the previous season.

GSK used their first-mover status to secure supply chain capacity and contracts ahead of Moderna's entry. These steps created barriers that have persisted into 2026. The narrowed CDC guidance has shifted the RSV vaccine segment away from blockbuster projections.

Sales now depend more heavily on reaching defined high-risk groups through targeted distribution. "The actual opportunity boils down to distribution and relationships.