Qualitative insights into vaccine hesitancy among striped catfish (Pangasianodon hypophthalmus) farmers in the Mekong Delta, Vietnam.

Vaccination has reduced reliance on antibiotics and chemical treatments in major aquaculture industries like salmon farming, yet adoption remains low in developing sectors such as the striped catfish (Pangasianodon hypophthalmus) industry in the Mekong Delta, Vietnam. This qualitative study examines Vietnamese striped catfish farmers' perspectives to uncover factors driving the low adoption of the available bivalent vaccine against Edwardsiella ictaluri and Aeromonas hydrophila. Between March and April 2023, semi-structured qualitative interviews were conducted with 44 purposively sampled Vietnamese striped catfish farmers across nursery and grow-out farms of different sizes and full spectrum of vaccination experience in the Mekong Delta region. The interviews covered the attitudes, knowledge, and use of vaccination among participants and were thematically analysed using the Framework method. The vaccine adoption landscape, visualised by adoption subgroups categorised in an adapted Precaution Adoption Process Model (PAPM), showed a clear skew toward non-uptake, represented by the prevalence of the 'Unengaged' and 'Informed sceptics' groups. The fragmented nature of the industry requires collaborative effort between nursery and grow-out stakeholders for effective vaccination. However, we identified a pervasive reluctance toward vaccine adoption in both groups of stakeholders, primarily due to cost-benefit concerns. Nursery farmers, bearing the costs of potential post-vaccination side effects, were hesitant to vaccinate fingerlings. Meanwhile, grow-out farmers questioned the cost-effectiveness of the vaccine. These concerns point to a critical need for interventions, either to alleviate perceived risks about vaccination or to develop alternative vaccine solutions that are more effective, user-friendly, and economical. Addressing these issues could reduce the economic impact of disease outbreaks and steer the industry towards reduced antibiotic use.