Students' psychological imperviousness may protect against the possible stigma associated with getting vaccinated for HIV, or other STDs, Ravert said.

'It is important to determine what factors are associated with vaccine acceptance because not all students will be willing to take vaccines,' said Ravert.

'Efforts to promote vaccines should consider that students who aren't worried about being harmed are less likely to get the vaccine, even when it's warranted by their sexual behaviour.'

In the study, the strongest predictor of vaccine acceptance was students' perceived susceptibility of contracting HIV, followed by their number of sexual partners. Students' decisions also were influenced by the cost of the vaccine.

These findings were published in the American Journal of Health Behaviour.