Will GSK Be Able to Resolve Its Vaccine Challenges Anytime Soon?

GSK is facing significant headwinds in its U.S. vaccine segment, with sales of its shingles vaccine Shingrix and RSV vaccine Arexvy declining 56% and 18% respectively in H1 2025, contributing to an 11% overall U.S. vaccine sales drop. This is primarily due to lower demand for Shingrix and revised, narrower ACIP recommendations for Arexvy, which also faces competition from Pfizer and Moderna's RSV vaccines with broader approvals for younger high-risk adults. Despite these challenges, GSK's stock has risen 19.2% year-to-date, trades at an attractive forward P/E of 8.68x, and boasts a promising long-term pipeline including the recently approved Penmenvy.

Analysis

GSK is facing significant operational headwinds in its U.S. vaccine business, which contrasts sharply with its strong year-to-date stock performance and attractive valuation. In the first half of 2025, U.S. sales of its shingles vaccine, Shingrix, and RSV vaccine, Arexvy, plummeted 56% and 18% respectively, driving an 11% overall decline in the company's U.S. vaccine sales. The weakness is attributed to challenges in reaching new consumers for Shingrix and, more critically, to revised June 2024 ACIP recommendations that narrowed the eligible population for Arexvy. This regulatory change, coupled with broader approvals for competing RSV vaccines from Pfizer and Moderna, puts GSK at a competitive disadvantage. Despite these challenges and a company forecast for the full-year 2025 vaccine segment to be flat to down a low single-digit percentage, GSK's stock has risen 19.2% year-to-date. The valuation appears compelling, with a forward P/E ratio of 8.68, substantially below the industry average of 14.78 and its own 5-year mean. While the long-term pipeline, including the recently approved Penmenvy vaccine, shows promise, it is not expected to materially contribute in the near term, leaving a disconnect between current operational performance and market valuation.

Key Decisions for Investors

• Investors should weigh the attractive valuation, marked by a forward P/E of 8.68, against the clear near-term revenue headwinds from declining U.S. sales of key vaccines Shingrix and Arexvy.
• Monitor U.S. immunization rates and any updates to ACIP guidelines, as these are the primary drivers of the current sales decline and represent the most significant risk to the vaccine segment's 2025 performance.
• Closely track the market share and sales data for Pfizer's Abrysvo and Moderna's mResvia, as their broader approved usage in younger high-risk adults poses a direct competitive threat to Arexvy.
• Consider the recent positive revisions in 2025 and 2026 earnings estimates as a potential buffer, but recognize that a long-term thesis relies on the successful commercialization of the pipeline, which will not offset current revenue pressures in the short term.