On the Spanish Island of Isla del Aire, scientists headed by veterinarian José Manuel Sánchez-Vizcaíno have captured 147 wild rabbits. First they implant a microchip in each that allows the scientists to monitor them. Then half the rabbits are vaccinated against two viral diseases. Finally all the rabbits are set free – including the ones that had no injection. A month later, the rabbits are tracked via their microchips, and captured again.
Much to the delight of the scientists, some 56% of the unvaccinated rabbits have become immune, despite not receiving an injection. And that’s because the vaccines are not the usual type: instead they are contagious, designed to spread through a community on their own – very like the viruses the vaccines are designed to stop.
The ground-breaking experiment with rabbits took place in 1999. But back then the scientists had difficulty selling
