New CDC vaccine advisers vote to recommend Merck RSV antibody protection for babies

The US CDC's newly reconstituted Advisory Committee on Immunization Practices (ACIP) voted 5-2 to recommend Merck's new RSV shot, clesrovimab (Enflonsia), for infants, a critical step towards widespread availability for the coming season. This decision, despite a split vote reflecting internal tensions within the controversial new panel, adds a significant tool against the leading cause of infant hospitalization. A subsequent unanimous vote to include the shot in the Vaccines for Children Program further broadens its market reach and ensures access for underserved populations, bolstering Merck's commercial prospects for the product.

Analysis

The U.S. CDC's Advisory Committee on Immunization Practices (ACIP) has recommended Merck's (MRK) new RSV antibody shot, clesrovimab, for infants, a pivotal step for its commercialization ahead of the upcoming RSV season. However, the recommendation was passed on a narrow 5-2 vote, revealing significant friction within the newly constituted and controversial panel appointed by Robert F. Kennedy Jr. This split reflects concerns raised by new members over safety data, which were countered by assurances from the FDA, Merck, and other panelists who praised the drug's efficacy as a 'spectacular accomplishment.' Despite the contentious primary vote, a subsequent unanimous decision to include the shot in the Vaccines for Children Program provides a crucial pathway for broad market access and uptake, significantly de-risking the launch. This development positions Merck to compete against two existing RSV interventions, but the political upheaval surrounding the ACIP, which has prompted criticism from organizations like the American Academy of Pediatrics, introduces a notable governance risk that could influence future policy and public trust.

Key Decisions for Investors

• The ACIP recommendation, particularly the unanimous vote for inclusion in the Vaccines for Children Program, is a significant positive catalyst for Merck, supporting a bullish case for the commercial launch of its RSV drug, Enflonsia.
• Investors should monitor the political and reputational risks associated with the new ACIP, as the contentious nature of the committee and criticism from established medical bodies could create headwinds for physician adoption or future immunization policies.
• While the recommendation is a key milestone, assess Merck's potential market share for Enflonsia in the context of the two existing competing RSV interventions for infants to accurately model its revenue contribution.