The new findings are fascinating, but they have only been demonstrated with one particular disease in animals, said Joanne Devlin, a veterinary virologist at the University of Melbourne in Australia, who was not involved in the study.
"I'd be wary of extrapolating too far into other systems," Devlin told Live Science. "We use vaccines a lot differently in humans than we do in animals, and the vaccines themselves are different."
For instance, animal vaccines are largely developed for agricultural purposes, so people don't care too much about saving every single animal or stopping all symptoms of disease; they just want to stop outbreaks to protect their bottom line. As a result, most animal vaccines are developed rapidly, and undergo fewer tests to show safety and effectiveness than those that are required for human vaccines. There are also more animal vaccines in use, Devlin said.
Many animal vaccines are known as leaky vaccines, which means they reduce symptoms but people can still be infected by the viruses. Most human vaccines, such as for polio, and the measles, mumps and rubella (MMR) vaccine are perfect vaccines, so they also stop transmission of the disease in question, Read said. (It's not clear why some vaccines are leaky, but diseases where the body does a good job of creating lifelong immunity after a single exposure, such as for childhood diseases like measles, seem to be more suited to the development of perfect vaccines, Read added.)
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