⚠ Vaxneuvance Fell 35% in a QuarterModerate threat

Merck & Co. (MRK) — threat to the moat

Vaxneuvance, Merck's paediatric pneumococcal vaccine, lost 35% of its quarterly sales in a year.

Vaxneuvance was Merck's route into the paediatric pneumococcal market. It sold $825 million in 20251. In the second quarter of 2026 it sold $148 million, down 35% from $229 million a year earlier2.

Vaxneuvance quarterly sales ($M)229Q2 2025148Q2 2026Merck Q2 2026 results release
A third of the quarter gone.

A decline of that size is unusual for a vaccine only a few years into its life. The drug did not lose a patent; it lost orders. Merck attributes the fall partly to unusually strong public-sector buying in the United States a year earlier and partly to lower demand "due to competitive pressure"3. In a market where an incumbent competitor sells several times Merck's pneumococcal volume, as the Competitors page shows, each tender and each pediatric schedule decision can move share quickly.

The broader vaccine line felt it: total vaccine sales were $2,361 million in the second quarter of 2026 against $2,370 million a year earlier4, flat while Merck's total sales grew 5%5.

The comparison with the incumbent is stark. Pfizer's Prevnar family sold $6,494 million in 2025, $4,151 million of it in the United States6, against Vaxneuvance's $825 million7. A challenger that loses a third of a quarter's sales against an incumbent eight times its size has little room to lose more.

The next two quarters of Vaxneuvance sales will show whether this is a timing effect or a trend. A third consecutive quarter of decline would mean the paediatric market is going to the incumbent's newer products.

References
  1. ReportedIt sold $825 million in 2025.
    Merck & Co. Form 10-K for fiscal 2025 - Item 7 MD&A and product sales note: sales by product, segment and country. — FY2025 · publ. 24 February 2026 · source ↗
  2. ReportedIn the second quarter of 2026 it sold $148 million, down 35% from $229 million a year earlier.
    Merck second-quarter 2026 results release, Form 8-K exhibit 99.1 - sales by product and pipeline highlights. — Q2 2026 · publ. 4 August 2026 · source ↗
  3. ReportedMerck attributes the fall partly to unusually strong public-sector buying in the United States a year earlier and partly to lower demand "due to competitive pressure".
    Merck second-quarter 2026 results release, Form 8-K exhibit 99.1 - sales by product and pipeline highlights. — Q2 2026 · publ. 4 August 2026 · source ↗
  4. ReportedThe broader vaccine line felt it: total vaccine sales were $2,361 million in the second quarter of 2026 against $2,370 million a year earlier, flat while Merck's total sales grew 5%.
    Merck second-quarter 2026 results release, Form 8-K exhibit 99.1 - vaccine and Animal Health sales. — Q2 2026 · publ. 4 August 2026 · source ↗
  5. ReportedThe broader vaccine line felt it: total vaccine sales were $2,361 million in the second quarter of 2026 against $2,370 million a year earlier, flat while Merck's total sales grew 5%.
    Merck second-quarter 2026 results release, Form 8-K exhibit 99.1 - vaccine and Animal Health sales. — Q2 2026 · publ. 4 August 2026 · source ↗
  6. ReportedPfizer's Prevnar family sold $6,494 million in 2025, $4,151 million of it in the United States, against Vaxneuvance's $825 million.
    Pfizer Form 10-K for fiscal 2025 - Prevnar family revenue of $6,494 million, $4,151 million in the U.S. — FY2025 · publ. February 2026 · source ↗
  7. ReportedPfizer's Prevnar family sold $6,494 million in 2025, $4,151 million of it in the United States, against Vaxneuvance's $825 million.
    Merck & Co. Form 10-K for fiscal 2025 - vaccines and China: Gardasil, the childhood and pneumococcal vaccines, and sales in China. — FY2025 · publ. 24 February 2026 · source ↗
Sources
Generated September 25, 2026