Disease prevention is a central challenge in aquaculture, and vaccination has been considered as the most effective tool to reduce the impact of infectious agents. Yet, the success of vaccination depends not only on antigen formulation and delivery methods, but also on how fish respond physiologically to the process. Depending on the application, vaccination itself can act as a source of stress, through handling, anesthesia, and injection, which may influence both immune protection and overall welfare. Additionally, some of the oil-based adjuvants, commonly used in aquaculture vaccines, may cause side effects that can affect animals’ welfare.

Physiological stress during and after vaccination procedures triggers the hypothalamic–pituitary–interrenal (HPI) axis, leading to elevated stress hormones, e.g., cortisol and adrenaline. Elevated cortisol and catecholamines can interfere with antigen presentation, lymphocyte proliferation, antibody production, and cytokine regulation, all of which are essential for mounting an effective adaptive immune response. As a result, fish may mount a weaker adaptive immune response, which likely would reduce vaccine efficacy in terms of antibody production, memory cell formation, and protection against pathogens. Therefore, minimizing stress before, during, and after vaccination through careful handling, optimized vaccination protocols and vaccine adjuvants, and supportive husbandry practices are crucial for maximizing vaccine performance and fish welfare.

The goal of this research is to better understand the mechanisms behind the negative effects of vaccination and to identify strategies to mitigate these effects. This can be achieved through experimental evaluation of stress and immune biomarkers, optimization of vaccination procedures and routes, optimization of vaccine adjuvants and antigens, and development of husbandry practices that minimize stress before, during, and after vaccination. This research topic can explore nutritional and natural strategies to mitigate the stress-induced effects of vaccination based on dietary supplementation e.g., tryptophan and essential oils, or new sedatives. Likewise, the scope of this research topic will include the reduction of stress during and after vaccination due to novel water-based adjuvants, innovative antigen formulation or vaccination routes. Impact of such reduction in stress can be evaluated through physiological stress markers and post-vaccination immune responses. By addressing the interplay between stress and vaccine response, this research will contribute to improving fish welfare, enhancing vaccine efficacy, disease prevention and ensuring more sustainable aquaculture production. Ultimately, integrating functional feeds with vaccination protocols could provide a sustainable approach to strengthening disease prevention in aquaculture.

Scope and information for authors:

This Research Topic focuses on the stress-inducing effects of vaccination in fish at both mucosal and systemic levels and on innovative strategies to enhance vaccine efficacy. We invite contributions that explore the physiological, molecular, and immunological mechanisms underlying stress responses during vaccination, as well as approaches to mitigate these effects. Themes of interest include nutritional interventions, alternative vaccination methods, adjuvants and protocols, husbandry practices to reduce handling stress, and biomarkers for assessing stress–immunity interactions.

We welcome a variety of manuscript types, including original research articles, reviews, short communications, and methodological papers. Submissions addressing both fundamental insights into neuroendocrine–immune interactions and applied solutions for aquaculture vaccination are encouraged. By integrating multidisciplinary perspectives, this Research Topic aims to advance knowledge on improving vaccine performance, promoting fish welfare, and ensuring sustainable aquaculture production.

Are you interested in contributing a manuscript to this Research Topic?

Increasing Fish Vaccine Effectiveness