Vaccine adjuvants as stand-alone immunoprophylaxis in strategies for 100-day rapid responses to future pandemics.

The COVID-19 pandemic accelerated vaccinology progress, driving rapid vaccine development for infectious and non-infectious diseases. However, challenges persist: malaria, HIV, and dengue lack fully effective vaccines, whereas influenza and tuberculosis face waning efficacy. Emerging pathogens and drug-resistant strains further highlight the need for improved vaccines, particularly those offering rapid deployment, broad immunogenicity, and durable protection against variants. Adjuvants can play a dual role in this context: as new stand-alone tools for an early response to a pandemic -aiming at the 100-days mission objective- and for prevention of anti-microbial resistance (AMR); and as traditional components enhancing the efficacy and breadth of vaccines. The understanding of their mechanisms of action and novel usage could address critical gaps in pandemic preparedness, especially for vulnerable populations like children and the elderly.