Oral Fish Vaccines: Advances in Encapsulation Technologies and Immunological Challenges

Oral fish vaccines represent a promising approach in aquatic vaccinology. Combined with chemical engineering advances on the technology and material properties of encapsulation, can facilitate fish immunization. Currently, several studies propose oral vaccination as an alternative to injectable vaccines, however, only few are available in the market as boosters. The oral route remains the most practical and economical approach yet having important limitations. Gastrointestinal degradation of the antigen, uneven distribution in aquafeed, lack of targeted drug delivery and limited scalability being the most important ones. Encapsulation is the answer to targeted drug delivery and antigen protection. Industrial applications of encapsulation such as ionic gelation or double emulsion remain limited due to high production cost. Bridging fish immunology with innovative chemical engineering techniques is critical for a practical solution in effective oral fish vaccines design. This review aims to advance toward the approval and commercialization of oral fish vaccines, analyzing advantages and limitations of current encapsulation techniques, as well as fish immune mechanisms that affect their success, underlining the need of an intersectoral collaboration between scientists of chemical engineering and fish immunology fields. This would be a critical step toward scalable, practical and sustainable aquaculture.