Annual influenza vaccination campaigns are a trusted tool in efforts to decrease the morbidity and mortality of influenza in the United States, with an effectiveness of 36 to 54% at preventing influenza-related outpatient medical visits and 41 to 55% at preventing influenza-related hospitalizations in adults during the most recent 2024-2025 season.1 Short of developing a universal influenza vaccine with effectiveness that spans multiple seasons and influenza subtypes, the development of seasonal influenza vaccines with improved effectiveness would constitute an important public health advance. Vaccine developers have leveraged the recent successes of the messenger RNA (mRNA) vaccine platform against Covid-19 and