Interim effectiveness of the 2025–2026 JN.1-targeted COVID-19 vaccine against medically attended COVID-19 in immunocompetent US adults (≥18 years) using a test-negative case-control design across 253 ED/UCs and 179 hospitals in 7 states (September 3–December 31, 2025).
VE against COVID-19-associated ED/UC encounters was **50%** (95% CI, 42%–57%) and against hospitalization was **55%** (95% CI, 41%–66%), at a median ~47 days post-vaccination. In adults ≥65 years, VE was 48% (ED/UC) and 53% (hospitalization).
- Interim analysis only; confidence intervals are wide and waning immunity beyond ~70 days cannot be assessed yet. - Antigen tests (lower sensitivity) were included for case ascertainment, which could misclassify some controls. - Immunocompromised individuals were excluded, limiting generalizability to that high-risk group.
The 2025–2026 COVID-19 vaccine provides meaningful additional protection—roughly halving the odds of a serious COVID-19 encounter—even among adults with prior immunity. Clinicians should encourage vaccination in all eligible adults, including those ≥65 years who carry the greatest hospitalization burden.
Explore related topics
