Protective Efficacy of Vaccines Against Grass Carp Hemorrhagic Disease: A Systematic Review and Meta‐Analysis

= 88.8%). Subgroup analyses showed that protective efficacy varied by publication period, immunisation route, vaccine platform, and GCRV genotype background. Sensitivity analyses and leave-one-out analyses indicated overall stable results, while publication bias tests suggested possible small-study effects. Descriptive evidence mapping showed a marked increase in GCRV vaccine studies in recent years, mainly focusing on DNA vaccines and subunit/peptide vaccines, with evidence concentrated on GCRV-II. Overall, GCRV vaccines can reduce post-challenge mortality in grass carp to a certain extent, but their protective efficacy is influenced by multiple factors. Future studies should improve antigen matching, standardise evaluation systems, and develop vaccines with both efficacy and field applicability.