The Yin-Yang arms of vaccines: disease-fighting power versus tissue-destructive inflammation.

The disease-fighting power of vaccines has defeated many pathogens and has been credited with global reduction of mortality and morbidity. However, most vaccine developments focus on the enhancement of effector responses with systemic inflammation and the consequences overlooked. Recent evidence shows that systemic inflammatory phenotypes, acute or chronic, are both detrimental and should be avoided if possible. Since noninvasive vaccination by painless delivery of nasal vaccines and skin patch vaccines could elicit potent protective immunity without inducing systemic inflammation, it can be predicted that vaccinology will increasingly see the abandonment of the 'needle-injection' paradigm for vaccine development. The findings that specific viral particles could rapidly remodel the tissue environment postinfection in favor of some pathogens with the capacity to suppress others illustrate the pressing need for a deeper understanding of the underlying mechanisms in order to unlock the full potential of immunological intervention.