5 Key Takeaways

• 1

  The 2025-2026 COVID-19 vaccine provided short-term protection against medically attended COVID-19 among immunocompetent adults.

• 2

  Vaccine effectiveness was estimated at 50% against COVID-19-associated emergency department encounters and 55% against hospitalizations.

• 3

  The study analyzed data from 253 ED/UC sites and 179 hospitals across 7 US states from September 3 to December 31, 2025.

• 4

  Findings indicated similar vaccine effectiveness among adults aged 65 years or older, with 48% against ED/UC encounters and 53% against hospitalizations.

• 5

  Limitations included potential misclassification of vaccination status and low hospitalization rates, affecting statistical power for critical illness estimates.