A new epidemiological model predicts the effectiveness of vaccines in preventing or eliminating infectious diseases in livestock. Scientists at the Roslin Institute have developed a new epidemiological model to investigate the effectiveness of vaccines for preventing, mitigating or eliminating infectious diseases in livestock. When appropriately applied, even imperfect vaccines can prevent, eliminate or largely reduce the prevalence of viruses, the model shows. The study has practical implications for the design of vaccines and vaccination programmes in livestock. Image When appropriately applied, vaccines can prevent, eliminate or largely reduce the prevalence of viruses. Multiplicative effect The goal of effective vaccination is not only to protect individuals from disease, but to decrease the risk and severity of disease outbreaks, and ultimately eradicate the disease. The model shows that combining diverse vaccine properties may have a multiplicative effect and thus be considerably more effective. This could be used to prevent outbreaks if the vaccine is applied as a preventive measure, or to eliminate disease spread if applied during outbreaks. Controlling a deadly pig virus The model was used to investigate the effectiveness of vaccines to combat Porcine Reproductive and Respiratory Syndrome (PRRS) virus, although many of the principles apply to other viruses and pathogens. The PRRS virus causes breathing problems and deaths in young animals and it is endemic in most pig-producing countries worldwide. Vaccines have mostly failed to stop the spread of the virus. The new model shows that the control or even elimination of PRRS through vaccination may well be within reach, as long as the vaccine sufficiently speeds up recovery and reduces virus replication. Veterinary vaccines often only confer limited immunity and thus may not prevent infection. In this study, we developed a model that combines epidemiological consequences of different vaccination strategies and different vaccine properties applied to livestock. The model is successful in predicting the effectiveness of vaccines in livestock. Professor Andrea WilsonPersonal Chair in animal disease genetics and modelling, Roslin Institute Freely available information A wiki-website aiming to provide scientists, veterinarians and the public with insight into the diverse factors influencing vaccine effectiveness in livestock has been developed by the scientists, as part of the European research project SAPHIR (Strengthening Animal Production and Health through Immune Response). The wiki contains a user-friendly interactive modelling app that illustrates how different types of vaccine and vaccination strategies may together influence how diseases spread. The study is published in the journal PLOS ONE. Related links Scientific publication Wiki page on vaccine effectiveness in the field Vaccine shows promise against widespread chicken disease About the Royal Dick School of Veterinary Studies The Royal (Dick) School of Veterinary Studies is a one-of-a-kind centre of excellence in clinical activity, teaching and research. Our purpose-built campus, set against the backdrop of the beautiful Pentland Hills Regional Park, is home to more than eight hundred staff and almost fourteen hundred students, all of whom contribute to our exceptional community ethos. The School comprises: The Roslin Institute The Global Academy of Agriculture and Food Security The Roslin Innovation Centre The Hospital for Small Animals Equine Veterinary Services Farm Animal Services Easter Bush Pathology The Jeanne Marchig International Centre for Animal Welfare Education We represent the largest concentration of animal science related expertise in Europe, impacting local, regional, national and international communities in terms of economic growth, the provision of clinical services and the advancement of scientific knowledge. Publication date 06 Sep, 2019
