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BSI's reaction to imperfect vaccines and virulence of viruses

Research published in PLOS Biology on 27 July 2015 raised the possibility that vaccines which do not block transmission of their target virus to un-vaccinated hosts may encourage the evolution of more virulent pathogens. The researchers examined this scenario in chickens using the Marek’s disease virus, and reported that in this model this could indeed be the case. The BSI have issued the following statement from our President, Professor Peter Openshaw.  This quote has been included in reports by the Mirror, Press Association, The Times (£) and Washington Post.

Professor Peter Openshaw, President of the British Society for Immunology and Professor of Experimental Medicine at Imperial College London, said:

“The effects of innovations are hard to anticipate, and this is an example. Many viruses circulate widely and generally do little or no harm – swine flu being an example. However, some unlucky individuals are highly susceptible to disease, including the un-vaccinated. This article shows a new twist to this effect, whereby chickens vaccinated against Marek's disease might harbour and spread infection and yet not suffer from it. Clearly, vaccines that allow this to happen are not ideal and need to be improved so that they confer widespread benefits to the population as a whole via ‘herd immunity’. Fortunately, most vaccines don’t do this and just protect everyone, including those who are not actually vaccinated.

“It’s important not to interpret this study as an argument against vaccination of our children against flu or any other disease. The standard vaccines that are in current use are safe and effective, and not prone to cause the emergence of more dangerous strains of viruses. Vaccines are amongst the safest and most cost-effective measures that we have to improve public health and protect from disease and it is vital that we achieve high vaccination rates to prevent the return of the many and terrible diseases that they prevent.”

This statement is in response to the following paper: Read et al. 2015. PLOS Biology. DOI: 10.1371/journal.pbio.1002198