Has the COVID-19 vaccine formulation changed since 2025?

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Last updated: November 13, 2026 • View editorial policy

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COVID-19 Vaccine Formulation Updates

The COVID-19 vaccine formulation DID change after 2024-2025, with new formulations approved for the 2025-2026 season targeting different viral variants.

Key Timeline of Vaccine Changes

The evidence clearly shows vaccine formulations have been updated annually to match circulating variants:

2024-2025 Season

The 2024-2025 vaccines targeted Omicron JN.1 lineage variants (JN.1 and KP.2 strains) 1. Specifically:

  • Moderna and Pfizer-BioNTech: KP.2 strain formulations
  • Novavax: JN.1 strain formulation

These were authorized/approved by FDA in August 2024 and recommended by ACIP in September 2024 1.

2025-2026 Season

New formulations were developed and approved for 2025-2026 targeting evolved variants 2:

  • Pfizer-BioNTech Comirnaty® LP.8.1
  • Moderna Spikevax LP.8.1 (and mNEXSPIKE)
  • Novavax Nuvaxovid LP.8.1

These became available in September 2025 and target the JN.1 variant with updated antigen design 3.

Clinical Performance of Updated Vaccines

The 2025-2026 formulations demonstrated:

  • 50% effectiveness against COVID-19-associated ED/UC encounters (95% CI: 42%-57%) 3
  • 55% effectiveness against COVID-19-associated hospitalization (95% CI: 41%-66%) 3
  • 68% effectiveness for KP.2-targeted vaccines in case-control studies (95% CI: 42%-82%) 4

In comparison, the 2024-2025 vaccines showed lower effectiveness over their season:

  • 26% effectiveness against ED/UC encounters (95% CI: 23%-29%) 5
  • 35% effectiveness against hospitalization (95% CI: 30%-40%) 5
  • 41% effectiveness against critical illness (95% CI: 28%-51%) 5

Why Annual Updates Matter

The continuous evolution of SARS-CoV-2 variants necessitates regular vaccine updates to maintain protection, particularly for high-risk populations 2. The improved effectiveness of the 2025-2026 formulations compared to the waning effectiveness of 2024-2025 vaccines demonstrates the clinical benefit of variant-matched formulations.

Important Caveats

  • Vaccine effectiveness wanes over time, even with updated formulations 5
  • Protection against infection is lower than protection against severe outcomes
  • Immunocompromised individuals show reduced vaccine effectiveness (24% against hospitalization) 5
  • The median time since vaccination in effectiveness studies was approximately 46-48 days, so longer-term protection data is still emerging 3

Bottom line: COVID-19 vaccines are reformulated annually based on circulating variants, similar to influenza vaccines. The 2025-2026 formulations represent a distinct update from the 2024-2025 vaccines, with improved effectiveness against contemporary variants.

References

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.