NEJM December 11 2026

NEJM articles:Volume 393No. 23December 11, 2025The provided text summarizes two distinct, large-scale, randomized controlled trials investigating the effectiveness of the high-dose inactivated influenza vaccine compared to the standard dose in older adults (aged 65 and older). Both studies sought to determine if the high-dose vaccine offered superior protection against severe clinical outcomes, primarily focusing on the composite primary endpoint of hospitalization for influenza or pneumonia. The Danish trial, involving over 330,000 participants, ultimately did not find a significantly lower incidence of this primary outcome with the high dose, although it noted a strong effectiveness against hospitalization specifically for influenza. Conversely, the Spanish trial, which focused on a slightly younger group (ages 65 to 79), concluded that there appeared to be fewer hospitalizations for influenza or pneumonia in those receiving the high-dose vaccine, suggesting conflicting findings regarding overall efficacy against severe complications.