Voluntary Vaccinations Worth a Shot

(Ivanhoe Newswire) -- A new study suggests voluntary vaccinations could be effective for some diseases.  Previous studies have suggested voluntary programs cannot be 100 percent effective due to self-interested behavior. 

In this new study, researchers looked at “free rider” effects under voluntary vaccination.  Individuals choose whether to vaccinate based on the risk of infection from their neighbors and any risks associated with the vaccine itself.   Neighbors of an infected person will vaccinate as soon as their neighbor’s symptoms appear, so when neighborhood size is small, voluntary vaccination results in rapid containment of an outbreak.  As neighborhood size increases, a threshold is reached beyond which the infection can break through due to the decisions of neighbors who choose not to vaccinate.

"This approach injects great realism into the transmission modeling of close contact infections and gives us a much more nuanced picture of how people’s behavior influences the effectiveness of voluntary versus mandatory vaccination policies," Chris Bauch, study author, researcher from the University of Guelph was quoted as saying.

SOURCE: PLoS Computational Biology, February 2009

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