1. Introduction
Human papillomavirus (HPV) vaccination has been introduced in over 100 countries and underlies the WHO’s global strategy for the elimination of cervical cancer.
The national HPV vaccination programme in England, launched in 2008, aims to reduce the incidence of cervical cancer and cervical intraepithelial neoplasia (CIN3), particularly by preventing persistent infections from high-risk HPV types 16 and 18, which are responsible for around 80% of cervical cancers in the UK. The programme initially offered the bivalent vaccine (Cervarix) to girls aged 12–13 years (in school year 8), with catch-up vaccination for girls aged 14–18 years, from 2008 to 2010. By targeting younger individuals who are most likely to benefit from the vaccine before any exposure to HPV, the programme sought to significantly reduce cervical cancer rates in the future. Over time, vaccine coverage varied, especially for the catch-up cohorts, but the initiative is a key part of global efforts to reduce the burden of cervical cancer.
2. Method
Data for cervical cancer and CIN3 diagnoses were extracted from a population-based cancer registry on January 26, 2021. Diagnoses from January 1, 2006, to June 30, 2019, in women aged 20–64 years who were residents of England were included in the analysis. The relative risk of cervical cancer in three vaccinated cohorts was estimated using an extension of the age-period-cohort Poisson model, with comparisons made to earlier cohorts that were not eligible for HPV vaccination. The vaccinated cohorts were categorized based on the school year in which the vaccine was offered, accounting for national vaccination coverage. Adjustments for confounding factors, including changes in cervical screening policies and historical events that influenced cervical cancer incidence, were made. Results were compared across models with varying adjustments for confounders.
Robust statistical models were used to compare different age and vaccination cohorts, with adjustments made for factors such as screening policies and cohort variations.
3. Key Findings / Results
The study demonstrated significant reductions in both cervical cancer and CIN3 incidence across vaccinated cohorts. The main findings are as follows:
- Cervical Cancer Reductions:
- For women vaccinated at ages 16–18 years, the relative risk reduction for cervical cancer was 34% (95% CI: 25–41%).
- For those vaccinated at ages 14–16 years, the reduction was 62% (95% CI: 52–71%).
- For the youngest cohort, those vaccinated at ages 12–13 years, the reduction was 87% (95% CI: 72–94%).
- CIN3 Reductions:
- In the cohort vaccinated at ages 16–18 years, there was a 39% (95% CI: 36–41%) reduction in CIN3 cases.
- In the 14–16 years cohort, the reduction was 75% (95% CI: 72–77%).
- The most striking reduction in CIN3 was observed in the 12–13 years cohort, with a 97% (95% CI: 96–98%) reduction.
By the end of the study period (June 30, 2019), the vaccination programme had resulted in 448 fewer cervical cancer cases and 17,235 fewer cases of CIN3 in vaccinated cohorts compared to unvaccinated cohorts.
4. Conclusion
The HPV vaccination programme in England has had a profound impact on reducing the incidence of cervical cancer and CIN3, particularly among women vaccinated at ages 12–13 years. These reductions indicate that the vaccine has successfully prevented these conditions in younger women, with near elimination of cervical cancer in those born after the programme’s initiation. The findings underscore the effectiveness of early vaccination and highlight the importance of continuing such programmes to achieve long-term public health benefits. These results also suggest that the success of vaccination strategies depends significantly on high coverage rates and early administration.
5. Discussion
The study’s findings are significant, as they provide direct evidence of the effectiveness of the HPV vaccination programme in reducing cervical cancer and CIN3 incidence. Key points from the discussion include:
- Effectiveness of the HPV Programme:
The study’s results validate the expected benefits of the HPV vaccine, particularly when offered at a young age (12–13 years), where the most substantial reductions in cervical cancer and CIN3 were observed. - Factors Influencing Results:
Several factors likely contributed to the observed reductions, including herd immunity, cross-protection against other HPV types, and vaccine coverage. Vaccinated women are not only protected but also reduce the overall HPV prevalence in the population, benefiting unvaccinated individuals as well. Additionally, cross-protection from the vaccine may offer protection against HPV types other than 16 and 18, further reducing cancer and pre-cancerous lesions.
These findings contribute to the growing body of evidence showing the effectiveness of HPV vaccination in preventing cervical cancer and related diseases, supporting the continued implementation and expansion of vaccination programmes globally.This study provides compelling evidence that the national HPV vaccination programme has significantly impacted public health, particularly in reducing the burden of cervical cancer and precancerous lesions in the UK.
Citation:
Falcaro, M., Castañon, A., Ndlela, B., Checchi, M., Soldan, K., Lopez-Bernal, J., Elliss-Brookes, L. and Sasieni, P. (2021). The effects of the national HPV vaccination programme in England, UK, on cervical cancer and grade 3 cervical intraepithelial neoplasia incidence: a register-based observational study. The Lancet, [online] 398(10316). doi:https://doi.org/10.1016/S0140-6736(21)02178-4.
