Perspective: Relax, there are no ‘contagious’ vaccines for humans

When National Geographic recently published an article about “contagious” vaccines, something resembling panic surfaced on Twitter. There was the sense that the piece was being shared by people who hadn’t actually read it, something that about 6 of 10 Americans are said to do.

As one person wrote indignantly, “Instead of catching a cold/flu, you catch a vaccine. Without consent!” And “what could possibly go wrong?” was the theme of the day.

The article in question, however, mostly involved efforts to stop the spread of disease among animals. It talked about a 1999 field trial on an island off the coast of Spain that was designed to see if a “self-spreading” vaccine could stop disease in wild rabbits. It was a small study, involving a cohort of 147 rabbits, but seemed to be a success. Researchers found that more than half of the unvaccinated rabbits in the study later had acquired antibodies that were presumed to have come from their mingling with vaccinated rabbits.

National Geographic reported that a person involved with the study said “that data from the laboratory and field trials showed the vaccine was safe and its spread remained confined to the rabbit populations.” The vaccine was not authorized for further use; however, since then, other researchers have worked on similar vaccines designed to stop the spread of disease in rats and monkeys.

Writing for the journal Trends in Microbiology in 2018, researchers James J. Bull, Mark Smithson and Scott Nuismer wrote that “vaccine transmission is easier than we think” despite the challenges that would have to be addressed, including the weakening of effectiveness over time.

“Most transmissible vaccines will simply die out unless continually introduced,” the scientists wrote, saying that transmissible vaccines could be “for humans or wildlife.”

But one scientist quoted in the National Geographic article was adamant that there would never be “contagious” vaccines developed for human use.

“We can’t even get people to take a vaccine in a global pandemic. The idea that you would be able to surreptitiously vaccinate the population with a virus without causing riots is just, you know, it’s stuff of fantasy. It will never be used in humans,” said Alec Redwood, a principal research fellow at the University of Western Australia.

The scientists quoted in that article also noted that there are ethical questions even with regard to the use of transmissible vaccines in animals — such as the risk of mutations and interruption of nature’s population control. Those would have to be overcome even if there was an ultimate societal good, such as diminishing the spread of animal-borne disease like rabies or Ebola.

That said, with the COVID-19 vaccination having become a political issue, there are surely public health officials who long for a world in which entire populations are made immune to disease through vaccination without attendant controversy. That desire comes up against the principle of informed consent, which holds that a person should be knowledgable about and able to give consent to any medical treatment.

With some people believing that the COVID-19 vaccine is part of a government conspiracy to track us, or make us magnetic, or do the bidding of Bill Gates, it’s understandable that research into making vaccines transmissible might cause a tinge of anxiety. And to be sure, there are plenty of things on the medical horizon that can legitimately keep us awake at night, including the prospect of animal farming for human organs and genetic editing of our descendants.

But for now, it looks like a transmissible vaccine for humans lies securely in the realm of science fiction, and there’s probably a screenwriter working on a movie script about this right now. But public health officials might appreciate one comment on on Twitter by a person who wrote: “Contagious vaccine? ... They’re making me want to wear a mask.”