Research in context
Evidence before this study
Randomised controlled trials and surveillance studies have shown the usefulness of Human Papilloma Virus (HPV) vaccination at preventing HPV infection and cervical intraepithelial neoplasia (CIN), but direct evidence of its effect on cervical cancer incidence is incomplete. Preliminary evidence that showed that vaccination protects against HPV-associated cancers was provided by a combined passive follow-up of women participating in two Finnish vaccination trials (one using the quadrivalent vaccine and the other the bivalent vaccine) compared with an unvaccinated cohort; however, the number of people with cancer was too small to estimate efficacy with precision. An analysis of cervical cancer rates in Sweden showed reduced risk of cervical cancer in individuals who received Gardasil (a quadrivalent HPV vaccine) but estimates of efficacy varied depending on the adjustments made.
Added value of this study
We observed a substantial reduction in cervical cancer and incidence of CIN3 in young women after the introduction of HPV immunisation in England, especially in individuals who were offered the vaccine at age 12–13 years. Our study provides the first direct evidence of the prevention of cervical cancer using Cervarix (a bivalent HPV vaccine). We defined our cohorts to account for the age at which women were offered HPV immunisation and the differences in national vaccination coverage. This definition allowed us to estimate the effect of the routine vaccination programme carried out in girls aged 12–13 years (school year 8) separately from the additional catch-up campaigns that targeted girls aged 14–16 years (school years 10–11) and 16–18 years (school years 12–13), who might have already been exposed to HPV before vaccination and among whom coverage was lower.
Implications of all the available evidence
Our findings add evidence to the very limited literature showing that national HPV immunisation programmes can lead to a substantial reduction in cervical cancer incidence, especially if vaccination coverage is high and women are offered the vaccine at a younger age. Although it is still too early to assess the full effect of the English HPV vaccination programme, our results contribute towards a better understanding and recognition of the benefits of HPV immunisation.