Washington, July 31 - College students who feel invincible or impervious to physical harm are likely to disdain vaccines to protect themselves against sexually transmitted diseases (STDs), including HIV and herpes.

Conversely, students who feel impervious to psychological harm or those who didn't care what others thought, are more likely to get the vaccine.

'Previous researchers have used invulnerability measures to predict health-endangering behaviours in students,' said Russell Ravert, assistant professor at the Missouri University (MU) College of Human Environmental Sciences who led the study.

'But this study is unique in that it considers the role of invulnerability in students' health-protective or preventative (sic) behaviours,' Ravert added.

Ravert measured two invulnerability factors - danger and psychological. Students who viewed themselves as physically invincible, were more likely to decline the vaccine.

One explanation is that strong feelings of danger invulnerability may be associated with decreased threat, which can diminish protective behaviours, Ravert said.