“The controversial quest to make a ‘contagious’ vaccine”
by Jess Craig
National Geographic, March 18, 2022
Scientists in the US and the UK have revived controversial research into vaccines that spread like diseases. Proponents for these “self-disseminating vaccines” say they could revolutionize public health and prevent the next pandemic. Others argue that these vaccines, some of which use genetically engineered viruses, could themselves mutate, jump species, or set off a chain reaction with devastating effects across entire ecosystems. I am writing to pitch a 2,000-word feature that will look at the current state of the research and consider both sides of the self-disseminating vaccine debate.
In the spring of 1999, veterinarian José Manuel Sánchez-Vizcaíno led a team of researchers to a remote island, Isla del Aire, off the coast of Spain. At the time, myxoma virus, which causes two deadly diseases called myxomatosis and rabbit hemorrhagic disease, was rapidly spreading through wild and domestic rabbit populations in Europe and China. While domestic rabbits, an important food source, could easily be culled to prevent the spread of disease, wild rabbits were considered nearly untreatable. On the island, Sánchez-Vizcaíno was testing a revolutionary new approach to end the devastation of myxoma using a transmissible vaccine. His team captured 147 rabbits, placed microchips in their necks, and administered a novel myxoma virus vaccine to half of them. They released all the rabbits and for the next 30 days allowed the vaccinated rabbits to interact, as usual, with the unvaccinated ones. When the researchers recaptured the rabbits, both the vaccinated and non-vaccinated ones had developed antibodies to the myxoma virus indicating that the vaccine had spread from those that were vaccinated to those that were not.
The experiment was considered the first proof-of-concept for self-disseminating vaccines, a broad term for vaccines that are engineered to spread through animal populations just as a virus would. Other trials followed showing that self–spreading vaccines could even prevent the spread of zoonotic diseases in animals before they got a chance to infect humans. After a brief period of excitement, the field went dormant. For one, pharmaceutical companies weren’t interested in a technology that, by design, would reduce its own profit margins. Moreover, the threat of zoonotic diseases remained largely unrecognized. But, in the next decades, we saw the 2003 SARS outbreaks, the 2014 Ebola epidemic, and an exponential rise in zoonotic infections such as H1N1 influenza and rabies which cost billions of dollars to contain and treat. In the past 30 years, 60% of new and emerging infectious diseases — Lyme disease, avian influenza, possibly COVID-19, among others — have crossed from animals to humans. In 2016, the European Union, US National Institutes of Health, and US Defense Advanced Research Projects Agency (DARPA) renewed funding for research into self-disseminating vaccines. Sánchez-Vizcaíno promptly resumed his work, this time to develop a self-disseminating vaccine against African swine fever which has caused billions of dollars in economic losses and forced farmers to cull millions of animals in the past year alone.
But some experts warn of catastrophic effects. Filippa Lentzos, a researcher in the Department of War Studies at King’s College London, says that without precautionary measures and proper oversight from the international community, self–spreading viruses could be developed quickly with limited funding and expertise and cause unknown and potentially irreversible consequences for the environment. There is also the bioweapons question. “The same research that is used to develop self–spreading vaccines to prevent disease, could also be used to deliberately cause harm,” Lentzos says.
I will draw from recent scientific articles and interviews with both advocates and critics of the technology. Sánchez-Vizcaíno and Lentzos will be key characters in the piece.
About myself: I am a former microbiologist and now freelance journalist. My work has appeared in National Geographic, Wired, Al Jazeera, The New Humanitarian, and NPR, among other publications.