Study cautions against self-spreading vaccines in poultry

The potential risks of using self-spreading vaccines against poultry disease outbreaks need to be explored before use in commercial and other real-world applications.

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JurgaR | iStockPhoto.com
JurgaR | iStockPhoto.com

The potential risks of using self-spreading vaccines against poultry disease outbreaks need to be explored before use in commercial and other real-world applications, warned a new policy paper published in Science.

“Self-spreading vaccine research continues to proceed despite a lack of new information that would compellingly refute long-standing evidence-based norms in virology, evolutionary biology, vaccine development, international law, public health, risk assessment and other disciplines,” the authors wrote.

“Providing such evidence, along with anticipated benefits, possible harms and risks, and appropriate precautionary measures, should have been considered a critical first step in undertaking self-spreading vaccine research.”

How self-spreading vaccines work

Self-spreading vaccines can confer protection against an infectious disease for an entire poultry flock, while requiring the vaccination of only a small subset if the population. The vaccines contain a genetically engineered virus that stimulates the creation of antibodies in the host, generating an immune response against infection.

The immune population can passively spread the positive effects of the vaccine to others through touch or breathing the same air.

Researchers have explored the use of self-spreading vaccines to control African swine fever in pigs and to prevent the spillover of animal pathogens into human populations. For example, if the deadly Lassa virus can be controlled through the vaccination of wild rats, the risks of a future outbreak in humans can be minimized.

For poultry, self-spreading vaccines could help protect against avian influenza or other disease outbreaks.

Yes, but what about potential containment breaches?

The poultry industry, along with other biomedical and agricultural sectors, should be cautious about research into self-spreading vaccines, the paper warned. There is still much that is not yet known about possible containment breaches, the potential of mutation or reversion to virulence, loss of efficiency or recombination with wild viruses.

“A clear priority for the international community must be to update existing phytosanitary, medical, and veterinary regulations to reflect contemporary societal values for responsible stewardship of science – and specifically with respect to environmental releases of self-spreading viruses,” the authors concluded.

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