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Effectiveness of 2024-2025 COVID-19 Vaccination Against COVID-19 Hospitalization and Severe In-Hospital Outcomes -
Kevin C Ma1, Alexander Webber1, Adam S Lauring2
1Coronavirus and Other Respiratory Viruses Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia.
Insights
The 2024-2025 COVID-19 vaccines demonstrated significant effectiveness against severe disease and hospitalization, even with evolving SARS-CoV-2 JN.1 descendant lineages. Vaccine protection remained robust, offering substantial defense against critical outcomes like invasive mechanical ventilation or death.
Area of Science:
- Virology and Immunology
- Vaccinology
- Public Health Surveillance
Background:
- Continuous evolution of SARS-CoV-2 JN.1 lineage necessitates ongoing evaluation of COVID-19 vaccine effectiveness (VE).
- Understanding VE against emerging variants is crucial for informing timely vaccine composition updates and public health strategies.
Purpose of the Study:
- To estimate the effectiveness of 2024-2025 COVID-19 vaccines against COVID-19-associated hospitalizations and severe in-hospital outcomes.
- To analyze VE across different time intervals post-vaccination, specific JN.1 descendant lineages (KP.3.1.1, XEC, LP.8.1), and spike mutations associated with immune evasion.
Main Methods:
- A test-negative, case-control study was conducted involving adult patients hospitalized between September 1, 2024, and April 30, 2025.
- Cases had COVID-19-like illness and a positive SARS-CoV-2 test; controls had similar symptoms but tested negative.
- Logistic regression was used to calculate adjusted odds ratios for vaccination in cases versus controls, estimating VE as (1 - adjusted odds ratio) x 100%.
Main Results:
- Overall VE against COVID-19-associated hospitalization was 40% (95% CI, 27%-51%), with sustained protection up to 179 days post-vaccination.
- VE against severe outcomes (invasive mechanical ventilation or death) was notably high at 79% (95% CI, 55%-92%).
- Effectiveness varied by lineage: 49% against KP.3.1.1, 34% against XEC, and 24% against LP.8.1, with similar VE observed for lineages possessing specific spike protein mutations.
Conclusions:
- The 2024-2025 COVID-19 vaccines provided significant additional protection against severe disease during the circulation of multiple JN.1 descendant lineages.
- Sustained vaccine effectiveness highlights the importance of updated vaccination for mitigating severe COVID-19 outcomes.
- Findings support the continued use of updated COVID-19 vaccines to combat evolving SARS-CoV-2 variants.
Importance:
As SARS-CoV-2 JN.1 lineage descendants continue to evolve, evaluating COVID-19 vaccine effectiveness (VE) against severe COVID-19 is necessary to inform vaccine composition updates.
Objective:
To estimate effectiveness of 2024-2025 COVID-19 vaccines against COVID-19-associated hospitalizations and severe in-hospital outcomes overall and by time since dose (7-89, 90-179, and ≥180 days), JN.1 descendant lineage (KP.3.1.1, XEC, LP.8.1), and spike mutations potentially associated with immune evasion.
Design Setting And Participants:
This test-negative, case-control analysis included adult patients hospitalized during September 1, 2024-April 30, 2025 at 26 hospitals in 20 U.S. states. Cases presented with COVID-19-like illness and a positive SARS-CoV-2 nucleic acid or antigen test; controls had COVID-19-like illness but tested negative.
Exposure:
Receipt of 2024-2025 COVID-19 vaccine ≥7 days before illness onset.
Main Outcomes And Measures:
Main outcomes were COVID-19-associated hospitalization and severe in-hospital outcomes (supplemental oxygen therapy, acute respiratory failure, intensive care unit admission, invasive mechanical ventilation [IMV] or death). Logistic regression was used to estimate the odds of vaccination in cases and controls adjusting for demographics, clinical characteristics, and enrollment region. VE was estimated as (1 - adjusted odds ratio) x 100%.
Results:
1,888 COVID-19 cases (including 348 with KP.3.1.1, 218 with XEC, and 134 with LP.8.1 infections) and 6,605 controls were enrolled (median [IQR] age, 66 [54-76] years; 4,338 [51%] female). VE against COVID-19-associated hospitalization was 40% (95% CI, 27%-51%) and protection was sustained through 90-179 days after vaccination. VE was higher against the most severe outcome of IMV or death at 79% (95% CI, 55%-92%). VE was 49% (95% CI, 25%-67%) against hospitalization with KP.3.1.1, 34% (95% CI, 4%-56%) against XEC, and 24% (95% CI, -19% to 53%) against LP.8.1, with increasing median time since dose receipt due to sequential circulation patterns (60, 89, and 141 days, respectively). VE was similar against lineages with spike protein S31 deletion (41% [95% CI, 22%-56%]) and T22N and F59S substitutions (37% [95% CI, 9%-57%]).
Conclusion And Relevance:
2024-2025 COVID-19 vaccines provided additional protection against severe disease as multiple JN.1 descendant lineages circulated.
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