The controversial quest to make a ‘contagious’ vaccine
Imagine a cure that’s as contagious as the disease it fights—a vaccine that could replicate in a host’s body and spread to others nearby, quickly and easily protecting a whole population from microbial attacks. That’s the goal of several teams around the world who are reviving controversial research to develop self-spreading vaccines.
Their hope is to reduce infectious disease transmission among wild animals, thereby lowering the risk that harmful viruses and bacteria can jump from wildlife to humans as many experts believe happened with SARS-CoV-2, the virus that caused the COVID-19 pandemic.
The U.S. Centers for Disease Control and Prevention estimates that 60 percent of all known infectious diseases and 75 percent of new or emerging infectious diseases are zoonotic. Scientists cannot predict why, when, or how new zoonotic diseases will emerge. But when they do, these diseases are often deadly and costly to control. What’s more, many researchers predict that climate change, biodiversity loss, and population growth will accelerate their spread.
Vaccines are a key tool for preventing diseases from spreading, but wild animals are difficult to vaccinate because each one must be located, captured, vaccinated, and released. Self-spreading vaccines offer a solution.
Advances in genomic technology and virology, and a better understanding of disease transmission, have accelerated work that began in the 1980s to make genetically engineered viruses that spread from one animal to another, imparting immunity to disease rather than infection.
Researchers are currently developing self-spreading vaccines for Ebola, bovine tuberculosis, and Lassa fever, a viral disease spread by rats that causes upward of 300,000 infections annually in parts of West Africa. The approach could be expanded to target other zoonotic diseases, including rabies, West Nile virus, Lyme disease, and the plague.
Advocates for self-spreading vaccines say they could revolutionize public health by disrupting infectious disease spread among animals before a zoonotic spillover could occur—potentially preventing the next pandemic.
But others argue that the viruses used in these vaccines could themselves mutate, jump species, or set off a chain reaction with devastating effects across entire ecosystems.
“Once you set something engineered and self-transmissible out into nature, you don’t know what happens to it and where it will go,” says Jonas Sandbrink, a biosecurity researcher at the University of Oxford’s Future of Humanity Institute. “Even if you just start by setting it out into animal populations, part of the genetic elements might find their way back into humans.”
Easy to understand explanations there.
Well that sounds like just a wonderful idea! What could possibly go wrong?! And it’s not like they can’t change their minds and recall it after it’s been unleashed on the world.