A study in BMJ in May 2024 reveals that HPV vaccination reduced rates of cervical cancer and pre-cancerous conditions in women in England. The observational study, led by researchers from Queen Mary University of London (QMUL), analysed data from NHS England for women between the ages of 20 and 64 between January 2006 and June 2020. Alongside finding that the vaccine reduced cervical disease, the study suggests that the vaccine was most effective when taken by people in Year 8 (aged 12 or 13), rather than later.
HPV and the vaccine
The authors state that human papillomavirus (HPV) comprises a family of viruses, within which is a subset responsible for “virtually all cervical and some anogenital and oropharyngeal cancers”. While “more than 100” countries have introduced prophylactic HPV vaccination within routine immunisation schedules, the authors were interested in whether vaccination has “reduced or increased the inequalities seen for cervical disease” in the UK and other regions.
The national HPV vaccination programme in England began in 2008 with the bivalent Cervarix vaccine for prevention of infections from HPV types 16 and 18. These two types are estimated to cause around 80% of all cervical cancers in the UK. Originally offered to 12-13-year-old girls and those under 19 years old, the programme switched to the quadrivalent Gardasil in 2012. In 2019 the programme was extended to include 12-13-year-old boys.
The authors comment that the way the programme has been introduced and implemented enables a “rigorous evaluation” of its effectiveness because “noticeable discontinuities exist”; women born in August 1990 may not have been vaccinated, but those born from 1st September of the same year are likely to have received at least one dose.
Positive effects
There is a “wealth of real-world evidence” of the early effect of the national HPV vaccination programme on HPV prevalence and a growing body of evidence on effectiveness in reducing high grade cervical intraepithelial neoplasia (CIN) and cervical cancer in vaccinated women. However, a key concern for the researchers was the reduction of health inequalities; they investigated whether the effect of immunisation against HPV has resulted in a reduction or “widening” in inequalities in cervical disease. If the uptake of HPV vaccination were to be lower in those at greatest risk of cervical cancer health inequalities could be exacerbated.
Indeed, previous studies suggest that the initial effect of the HPV immunisation programme was increased inequity HPV related cancer incidence among ethnic minority groups in England because of the “differential effect of herd protection with dissimilar vaccination coverage”. Further research indicates that “white people have a higher awareness of HPV and acceptance of the immunisation”. However, data on HPV vaccination coverage by local area did not show variation by deprivation score.
“A full understanding of the effect of HPV vaccination across different socioeconomic groups is complicated by the poor uptake of cervical screening observed among younger women in the most deprived areas, leading to lower rates of screen detected cervical cancer and CIN3 at age 25 years compared with women in less deprived areas.”
The current study evaluated if the high effectiveness of the programme continued during a further year of follow-up and investigated the effect of the programme by socioeconomic deprivation.
What does the study find?
“In England, the social-class gradient for cervical cancer is one of the steepest of any cancers: women in the most deprived fifth have had double the risk of those in the least deprived fifth.”
This is attributed to differences in exposure to HPV and risk of infection becoming persistent, but also “differential uptake of cervical screening”. The need for “new engagement strategies” has been highlighted. However, a positive note is that coverage of HPV vaccination was, at least until before the COVID-19 pandemic, “uniformly high”.
The authors found that previously identified high vaccination effectiveness was “confirmed” in the more recent data. Between 1st January 2006 and 30th June 2020, 29,968 women between 20 and 64 received a diagnosis of cervical cancer and 335,228 received a diagnosis of CIN 3. In the cohort of women offered routine vaccination, adjusted age standardised incidence rates of cervical cancer were 83.9% lower than the reference cohort. For CIN3 the cohort that were offered the routine vaccination had 94.3% lower incidence rates.
By mid-2020, HPV vaccination had prevented an estimated 687 cervical cancers and 23,192 CIN3s. Although the HPV vaccination programme had a “large effect” in all five levels of deprivation, the highest rates did remain among women living in the most deprived areas.
Three key factors
The authors suggest that observed incidences of cervical cancer and CIN3 depend on “three key factors”:
- Intensity of exposure to HPV infections (including age at first exposure)
- Uptake of cervical screening
- HPV vaccination coverage
They recognise that it is “difficult to disentangle” the effects of these three on the index of multiple deprivation specific rates with available data.
The power of vaccination
Professor Peter Sasieni, lead author from QMUL, commented that the research “highlights the power of HPV vaccination” for “people across all social groups”. Professor Sasieni recognised that cervical cancer has had “greater health inequalities than almost any other cancer”, noting concern that the vaccination programme “may not reach those at greatest risk”.
“Instead, this study captures the huge success of the school-based vaccination programme in helping to close these gaps and reach people from even the most deprived communities.”
Professor Sasieni emphasised that elimination of cervical cancer in the UK is “possible with continued action to improve access to vaccination and screening for all”. Cancer Research UK senior health information manager, Sophia Lowes, urged continued “momentum” to bring about a “future virtually free from this disease”.
“We’re calling for targeted action to ensure that as many young people as possible get the lifesaving HPV vaccine. Better reporting on uptake by deprivation and ethnicity, along with more research, will help us understand how to reach those most at risk.”
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