Model predicts vaccine effectiveness in animals
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.
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.
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.
** The Roslin Institute receives strategic investment funding from the Biotechnology and Biological Sciences Research Council and it is part of the University of Edinburgh’s Royal (Dick) School of Veterinary Studies. **
Related links
Wiki page on vaccine effectiveness in the field