COVID-19 Vaccine Recommendation Change for Infants in 2024-2025
The COVID-19 vaccine recommendation for infants was changed for the 2024-2025 formulation primarily because SARS-CoV-2 continues to evolve, with Omicron JN.1 lineage strains (including JN.1 and KP.2) now widely circulating instead of the previous XBB.1 strains, and because vaccine effectiveness is known to wane over time. 1
Viral Evolution Necessitating Updated Vaccines
The change in recommendation reflects the ongoing evolution of the SARS-CoV-2 virus:
- The previous 2023-2024 COVID-19 vaccines contained a monovalent XBB.1.5 component 2
- Since winter 2023-2024, Omicron JN.1 lineage strains (JN.1 and KP.2) have become predominant 1
- The FDA approved and authorized new 2024-2025 COVID-19 vaccines in August 2024:
- Moderna and Pfizer-BioNTech vaccines based on the KP.2 strain
- Novavax vaccine based on the JN.1 strain 1
Evidence of Waning Effectiveness Against New Variants
Research demonstrated that the previous vaccine formulation had reduced effectiveness against newer variants:
- VE against JN.1 lineage infection (37%) was lower than against XBB-sublineage infection (58%) 1
- VE against hospitalization declined from 49% at 7-59 days post-vaccination to just 14% at 120-179 days 1
- A study specifically comparing effectiveness showed 54.2% protection against XBB lineage hospitalization but only 32.7% against JN.1 lineage hospitalization 3
Continued Risk to Infants
Despite overall decreases in COVID-19 severity since the pandemic began, infants remain at elevated risk:
- During October 2023-May 2024, COVID-19-associated hospitalization rates were highest among adults ≥75 years, followed by infants <6 months 1
- In 2023,58 COVID-19-associated deaths were reported among infants <1 year 1
- Among hospitalized children with COVID-19, only 25% of infants <6 months had underlying conditions, suggesting otherwise healthy infants remain vulnerable 1
Recommendation Details
The Advisory Committee on Immunization Practices (ACIP) made the following recommendations:
- On June 27,2024, ACIP recommended 2024-2025 COVID-19 vaccination for all persons ≥6 months 1
- Children aged 6 months-4 years need an initial multidose vaccination series including at least one dose of the 2024-2025 COVID-19 vaccine to be considered up to date 1
- The FDA authorized these updated vaccines for children aged 6 months-11 years under Emergency Use Authorization in August 2024 1
Clinical Implications
Healthcare providers should note:
- The recommendation prioritizes protection against severe COVID-19-associated illness and death, which remains a concern for infants
- The updated vaccines target currently circulating strains, providing better protection than previous formulations
- Vaccination schedules vary based on age and previous vaccination history, with detailed guidance available in the ACIP recommendations
The change represents the ongoing adaptive response to an evolving virus, ensuring that the most vulnerable populations, including infants, receive optimal protection against current circulating strains.