We know it's effective. So why is there opposition to the HPV vaccine ?

Over 90% of cervical cancers are caused by HPV. But squeamishness about sex and unsupported safety fears are threatening vaccination programmes

Human papillomavirus (HPV) has long haunted humankind; almost all sexually active adults carry some of HPV's 170 strains. And although many of these are harmless, amongst the myriad mutants there are those whose effects are anything but benign: subtypes 6 and 11 can lead to genital warts; subtypes 16 and 18 (amongst others) can lead to cervical, vulvar, vaginal, penile, anal and oral cancers. This is not some mere hypothetical risk - over 90% of cervical cancers are caused by HPV, a cancer which claimed the lives of 270,000 women in 2012 alone.

Luckily, the HPV vaccine Gardasil is extraordinarily effective at preventing infection, being at least 99% effective against the four most odious subtypes (6,11,16,18) in young women. Yet despite this, it has been the subject of dogged opposition - in the US, vaccination rates have stagnated far below the optimum levels for protection, while a number of legal challenges against the vaccine have been mounted across Europe. But why is this the case?