COVID-19 2024-2025 Vaccines 33% Effective Against Hospitalization, ED Visits in Adults: Early Data
CDC midseason data suggest low COVID-19 vaccine efficacy in adults aged 18 to 64 years, with somewhat better impact on those aged 65 years and older.
Midseason vaccine effectiveness (VE) data from the CDC for the 2024-2025 COVID-19 season reveals that the current shot was only 33% effective in preventing COVID-related emergency department (ED) or urgent care (UC) visits in adults aged 18 to 64 years, and it was 45% to 46% protective against hospitalization for adults aged 65 years and older. VE against hospitalizations in immunocompromised adults in the older age group was 40%.
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The early report was published online in Morbidity and Mortality Weekly Report, with the caveat that data are currently too limited to provide estimates of VE in some groups.
COVID-19 vaccination was responsible for 68,000 fewer hospitalizations during the 2023-24 respiratory virus season, the authors wrote. The CDC- recommended vaccines during that season targeted the Omicron JN.1 and JN.1-derived sublineages, which were "genomically divergent from the XBB lineages on which the 2023–2024 COVID-19 vaccines were based," the authors wrote. The monovalent vaccines recommended by the Advisory Committee on Immunization Practices and approved by the CDC were made by Moderna and Pfizer-BioNTech, based on the Omicron KP.2 sublineage, and by Novavax, based on the JN.1.
VISION, IVY Databases
CDC researchers culled data from 2 multisite databases observed from September 2024 through January 2025 for outcomes among adults aged 18 years and older: the Virtual SARS-CoV-2, Influenza, and Other respiratory viruses Network (VISION) and Investigating Respiratory Viruses in the Acutely Ill (IVY) networks. VISION includes 373 EDs/UCs and 241 hospitals in 8 states, while IVY includes 26 hospitals in 20 states.
Among adults in the VISION network, researchers identified 137,543 encounters meeting criteria for inclusion in the analyses, including 10,459 (8%) case-patients and 127,084 (92%) control patients.
VE Higher for Adults 65 Years and Older
Effectiveness of 2024-25 COVID-19 vaccination against a COVID-19–associated ED/UC visit was 33% (95% CI, 28% to 38%) during the first 7 to 119 days after vaccination, 36% (95% CI, 29% to 42%) during the first 7 to 59 days after vaccination, and 30% (95% CI, 22% to 37%) during the 60 to 119 days after vaccination. Among the immunocompetent adults aged 65 years and older in VISION, VE was significantly higher, at 45% (95% CI, 36% to 53%) a median of 53 days following vaccination. For adults older than age 65 with immunocompromising conditions in VISION, VE was 40% (95% CI = 21%–54%), at the same interval of 53 days following a 2024–2025 COVID-19 vaccination.
In their analyses of the IVY network, the researchers found VE against COVID-19–associated hospitalization was 46% for adults over age 65 without immunocompromising conditions (95% CI, 26% to 60%), at a median of 60 days after receipt of a 2024-25 COVID-19 vaccine dose.
The authors explained that statistical power to estimate VE against hospitalization was limited in adults aged 18–64 years, thus the team estimated VE against hospitalization only for adults aged 65 years and older in both networks. In the IVY network, VE against hospitalization was estimated in immunocompetent adults due to limited statistical power to assess VE for immunocompromised adults; in VISION, VE was estimated for all adults in the ED/UC setting and separately for adults with and without immunocompromising conditions in the hospital setting.
Rates Lower than Previous Years
"COVID-19–associated hospitalization rates during the time frame of this analysis were relatively low compared with those during previous years, precluding estimation of VE against critical illness (ie, intensive care unit admission, invasive mechanical ventilation, or death); VE against these outcomes has historically been higher and more sustained than that against less severe outcome," the authors wrote.
They also note that the current analyses did not account for previous SARS-CoV-2 infection or previous COVID-19 vaccination (e.g., original monovalent, bivalent, or 2023–2024 doses). The VE estimate offered in this report, therefore, should be interpreted as "the added benefit of 2024–2025 COVID-19 vaccination in a population with high levels of infection-induced immunity, vaccine-induced immunity, or both."
