⚠ The CDC Split the MMRV ShotLow threat

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

Merck makes both the combined and the separate childhood shots, so the 2025 schedule change moved sales rather than removing them.

In September 2025 the CDC's Advisory Committee on Immunization Practices voted to recommend that children under four receive varicella protection as a standalone immunisation rather than combined with measles, mumps and rubella, and the acting CDC director adopted the recommendation in October 20251. The committee also aligned the Vaccines for Children programme with the change2.

ProQuad, M-M-R II and Varivax growth (%)+5.7%2023+4.9%2024-1.4%2025Calculated from Merck Forms 10-K FY2023 and FY2025 product sales
Growth turned slightly negative.

For Merck the arithmetic is mostly neutral, because it makes both the combined ProQuad and the standalone Varivax, and it expects the effect on ProQuad not to be material3. The risk is the precedent. The same body ended the universal birth-dose recommendation for hepatitis B vaccination in December 20254.

A vaccine maker's demand is set by recommendations it does not control. Merck's childhood vaccine line sold $2,451 million in 20255.

Insurers have promised to keep paying for now. The trade association of American health insurers said its members' plans would continue to cover all immunisations recommended by the CDC's advisory committee as of 1 September 2025, with no cost-sharing for patients through the end of 20266. That promise has an end date that falls well before any of Merck's vaccine patents.

Any further schedule change that reduced the number of doses rather than moving them between products is what to watch; that would reduce volume for a franchise with no domestic competitor to take share from.

References
  1. ReportedIn September 2025 the CDC's Advisory Committee on Immunization Practices voted to recommend that children under four receive varicella protection as a standalone immunisation rather than combined with measles, mumps and rubella, and the acting CDC director adopted the recommendation in October 2025.
    Merck & Co. Form 10-K for fiscal 2025 - Item 1A risk factors, patents and exclusivity, government pricing, vaccine policy and legal proceedings. — FY2025 · publ. 24 February 2026 · source ↗
  2. ReportedThe committee also aligned the Vaccines for Children programme with the change.
    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 ↗
  3. ReportedFor Merck the arithmetic is mostly neutral, because it makes both the combined ProQuad and the standalone Varivax, and it expects the effect on ProQuad not to be material.
    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 ↗
  4. ReportedThe same body ended the universal birth-dose recommendation for hepatitis B vaccination in December 2025.
    Merck & Co. Form 10-K for fiscal 2025 - Item 1A risk factors, patents and exclusivity, government pricing, vaccine policy and legal proceedings. — FY2025 · publ. 24 February 2026 · source ↗
  5. ReportedMerck's childhood vaccine line sold $2,451 million in 2025.
    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 ↗
  6. ReportedThe trade association of American health insurers said its members' plans would continue to cover all immunisations recommended by the CDC's advisory committee as of 1 September 2025, with no cost-sharing for patients through the end of 2026.
    Merck & Co. Form 10-K for fiscal 2025 - Item 1A risk factors, patents and exclusivity, government pricing, vaccine policy and legal proceedings. — FY2025 · publ. 24 February 2026 · source ↗
Sources
Generated September 25, 2026