He notes that the virus can be transmitted by sex, and that it's impossible to know the extent to which the effects of a vaccine would be passed on to other species. Still, McRae notes, "This is the first time I've seen a study where it has been shown that a vaccination agent can cause sexual behavior changes in humans."
However, scientists from Erasmus University Medical Centre in Rotterdam found that some of these animals had not developed normal sperm cells. The research was presented at the meeting of the European Society for Human Reproduction (ESM 2013).
