Estimated Effectiveness of 2024-2025 COVID-19 Vaccines in Adults

What was the effectiveness of 2024-2025 COVID-19 vaccines against medically attended COVID-19 among adults 18 years and older in the US?In this test-negative case-control study among immunocompetent adults with 333 262 emergency department/urgent care encounters and 97 663 hospitalizations, estimated vaccine effectiveness (VE) was 26% against COVID-19–associated emergency department/urgent care encounters, 35% against COVID-19–associated hospitalization, and 41% against COVID-19–associated critical illness 7 to 299 days after vaccination, and was higher 7 to 59 days after vaccination, with evidence of waning with more time since vaccination. Estimated VE against COVID-19–associated hospitalization among immunocompromised adults was 24%.Receipt of 2024-2025 COVID-19 vaccination was associated with additional protection against medically attended COVID-19 beyond an individual’s existing immunity; however, protection appeared to wane over time.

Corresponding Author: Ryan E. Wiegand, PhD, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd NE, MS H24-5, Atlanta, GA 30329 (rwiegand@cdc.gov).

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