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Optimization of vaccine responses in early life: the role of delivery systems and immunomodulators
1World Health Organization Collaborating Centre for Neonatal Vaccinology, Department of Pathology, University of Geneva, Switzerland. jiri.kovarik@medecine.unige.ch
Insights
Infant immunization faces challenges due to lower vaccine efficacy in newborns. Selective adjuvants show promise for improving infant vaccine responses and overcoming early-life immune limitations.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Infant immunization is critical but complicated by high infection susceptibility and reduced vaccine efficacy in newborns.
- Early-life immune responses are often biased towards Th2, potentially hindering effective vaccination against various pathogens.
Purpose of the Study:
- To review challenges in infant immunization and the role of selective adjuvants in overcoming these hurdles.
- To explore how adjuvants can enhance infant vaccine efficacy, duration of response, and safety.
Main Methods:
- Review of existing literature on infant immunization challenges.
- Analysis of data from experimental models and clinical studies on novel vaccine formulations and adjuvants.
Main Results:
- Selective adjuvants can potentially improve antibody responses, T-cell activation (Th1/CTL), and overcome maternal antibody interference.
- Adjuvants may enable multi-antigen vaccines, reducing injection frequency while maintaining safety and efficacy.
Conclusions:
- Adjuvants are crucial for developing effective infant vaccines by addressing specific immunological challenges of early life.
- Current research focuses on adjuvant strategies to optimize infant immunization outcomes and broaden vaccine applicability.
Abstract:
Infant immunization is a particularly important field with multiple challenges for vaccine research and development. There is, together with a high susceptibility to infections, a lower efficacy of most vaccinations in newborns and young infants, compared to those performed later in life. In the present review, the authors focus on problems arising from the attempt to vaccinate against pathogens very early in life, and on the role of selective adjuvants (i.e. antigen delivery systems or immunomodulators) that could be used to: (i) rapidly induce strong antibody responses of the appropriate isotypes; (ii) elicit sustained antibody responses extending beyond infancy; (iii) induce efficient Th1 and CTL responses in spite of the preferential Th2 polarization of early life responses; (iv) escape from maternal antibody mediated inhibition of vaccine responses; (v) show acceptable reactogenicity in early life; and (vi) allow incorporation of several vaccine antigens into a single formulation so as to reduce the number of required injections. How such objectives might be achieved by several of the vaccine formulations currently in development is illustrated by reviewing data from experimental models and clinical studies, when available.