COVID-19 Vaccine Recommendation: KP.2 vs JN.1 Strain
Get whichever 2024-2025 COVID-19 vaccine is available to you—both the KP.2-based (Moderna/Pfizer-BioNTech) and JN.1-based (Novavax) vaccines are FDA-authorized and ACIP-recommended as equivalent options for protecting against currently circulating strains. 1
Why Both Vaccines Are Acceptable
The Advisory Committee on Immunization Practices (ACIP) explicitly recommends 2024-2025 COVID-19 vaccination with any FDA-approved or authorized vaccine targeting the Omicron JN.1 lineage for all persons aged ≥6 months. 1 This recommendation does not prioritize one formulation over the other because:
Both target the same viral lineage: KP.2 is a descendant of JN.1, meaning both vaccines target closely related strains within the JN.1 lineage that are currently circulating in the United States. 1, 2
No comparative effectiveness data exists: The ACIP made their recommendation without evidence suggesting superiority of one formulation over the other—they are considered interchangeable for the purpose of protection against severe disease. 1
The primary goal is protection against severe outcomes: Both vaccines provide protection against COVID-19-associated hospitalization and death, which are the most critical outcomes for reducing morbidity and mortality. 1, 2
Expected Vaccine Performance
Regardless of which formulation you receive, understand the realistic protection levels:
Moderate effectiveness against symptomatic infection: Previous data on updated formulations showed 37% effectiveness against JN.1-sublineage infection at 60-119 days post-vaccination. 1, 2
Better protection against hospitalization: Effectiveness against COVID-19-associated hospitalization is 49% at 7-59 days after vaccination, declining to 14% at 120-179 days. 1, 2
Most durable protection against critical illness: Protection against severe disease is 69% at 7-59 days and 32% at 120-179 days after vaccination. 1, 2
Modest protection against death: Pooled vaccine effectiveness against COVID-19-associated death was 23%. 1, 2
Practical Guidance for California
Simply get vaccinated with whichever 2024-2025 formulation your pharmacy or clinic has in stock. 1 Do not delay vaccination waiting for a specific formulation, as:
Both Moderna and Pfizer-BioNTech (KP.2-based) vaccines are FDA-approved for ages ≥12 years and authorized under EUA for children 6 months-11 years. 1
Novavax (JN.1-based) is FDA-authorized under EUA for persons aged ≥12 years only. 1
The benefit of timely vaccination outweighs any theoretical advantage of one strain formulation over another, especially given that vaccine effectiveness wanes over time. 1, 2
Important Caveats
Age restrictions matter: If you are under 12 years old, only the mRNA vaccines (Moderna/Pfizer-BioNTech KP.2-based) are authorized for your age group. 1
Novavax requires 2 doses if vaccine-naive: If you have never received any COVID-19 vaccine and choose Novavax, you need 2 doses of the 2024-2025 formulation to be up to date. 1
Evidence certainty is low: The certainty of evidence for vaccine effectiveness is rated as low for most outcomes, meaning the true effectiveness may differ from these estimates. 1, 2