A study found fewer than half of some high-risk women attending sexual health clinics had been offered the vaccine, despite the existence of a national HPV vaccination programme.
Completion rates were lower than the national average among those who initially accepted the jab.
Experts said the vaccine should routinely be offered in sexual health clinics to boost vaccine coverage and prevent more cases of cervical cancer.
The study, published in the journal Sexually Transmitted Infections, drew on data from 2,247 young women aged 13-19 who had attended sexual health clinics between March and August 2011.
These women were more likely to smoke, have had sex for the first time under the age of 16 and have a previous STI; all risk factors for developing cervical cancer.
Even though all of the women at the clinics were supposed to have been offered the vaccine under the national programme, just 74% reported being offered the jab.
Proportion of women at sexual health clinics offered the HPV jab
|17-19 year olds: 67%|
|Living in London: 66%|
|Non-white ethnicity: 64-69%|
|Previous STI: 63%|
Source: Imperial College Healthcare NHS Trust
The researchers from Imperial College Healthcare NHS Trust in London found offer rates were as low as 49% among women not in education, employment or training (NEETs).
Offer rates were also low among young women in London, smokers, non-white ethnicities, 17- to 19-year-olds and those with previous STIs (see table).
When offered the jab, only 65% accepted and completion rates were far lower than the national average.
Study authors said: ‘Our work suggests that sexual health services may be useful additional vaccination delivery venues, but studies are needed to demonstrate that sexual health services can successfully deliver the course.’
Peter Greenhouse of the British Association for Sexual Health and HIV (BASHH) said: ‘The introduction of universal HPV vaccination for school-age girls will be one of the great public health success stories in the UK.
'But if vaccination rates are lowest for those at highest risk of cervical cancer and genital warts, we need to catch these women when they fall through the gaps: so the obvious place to do that is when they attend sexual health clinics.’
The HPV vaccination campaign for schoolgirls aged 12-13 was introduced in 2008. Just 66% completed all three doses in 2011, when the study took place. Latest figures show this rose to 86% by 2013, above the level needed to start preventing cervical cancer deaths.