Combining quantitative and qualitative approaches to determine viability of a potential Salmonella Typhimurium vaccination program in pigs in Belgium

Vaccinating pigs against Salmonella Typhimurium (ST) might be a way to control ST infections at farm level and reduce human infections. Two main issues have to be addressed before such a mandatory vaccination program can be implemented: the effective reduction of attributable human incidence has to be demonstrated and all socio-economic barriers impacting the attitude and motivation of the pig sector have to be lifted. The present research used a quantitative microbial risk assessment model to estimate the effect of different hypothetical Salmonella spp. and ST mitigation strategies on the annual prevalence of human salmonellosis along the minced pork production chain. In addition, a qualitative study aimed to list the potential concerns of the pig sector about the implementation of a hypothetical future vaccination program. The following themes were the most often mentioned: awareness, vaccine cost-benefit/effectiveness, legislation, monovalent vaccine, time and labour required to vaccinate, vaccine registration and trade restriction. Cost-effectiveness and cost-benefit of vaccination were cited by all the key interviewees (n = 12). However, based on the quantitative microbial risk assessment model, vaccination alone may not be sufficiently effective to reduce the annual human salmonellosis prevalence. A combination of different control measures along the food chain, with a special focus on interventions at the slaughterhouse, might be more effective in achieving the desired goal than vaccination alone.