A vaccine composition comprising a virus antigen wherein the composition comprises less than 5% serum, wherein the virus antigen is a whole virus or derived from a whole virus, the vaccine composition reduces, prevents or avoids cross-stitch spinal deformity in the treated animal. Said vaccine composition for use in a method of treating a disease caused by the intracellular pathogen in an animal and reducing, preventing or avoiding cross-stitch spinal deformity in the treated animal. In cross-stitch vertebra the intervertebral space is completely collapsed. A vaccine composition for use as defined above wherein the animal is a fish. In an embodiment the pathogen is salmon alpha virus (SAV).