New study shows continued high effectiveness of HPV vaccination in England

The human papillomavirus (HPV) vaccination program in England has not only been associated with a substantial reduction in cervical disease, but has done so in all socioeconomic groups, finds a study published by The BMJ.

Although women living in the most deprived areas are still at higher risk of cervical disease than those in less deprived areas, the results show that well-planned and executed public health interventions can both improve health and reduce health inequalities.

HPV is one of the most common sexually transmitted infections. Many countries, including the UK, now offer routine vaccination to girls and boys at age 12–13 to protect them against strains that can cause cancer in later life.

In England, the HPV vaccination program began in 2008, with catch-up vaccination for 14–18-year-olds from 2008–10. But because cervical cancer rates have always been higher in the most deprived groups, there is concern that HPV vaccination could benefit those at greatest risk of cervical cancer the least.

To address this, researchers analyzed cancer data from NHS England for vaccinated and unvaccinated women aged 20–64 years resident in England between January 2006 and June 2020 to examine whether the already high HPV vaccination effectiveness continued in an additional year of follow-up, from July 2019–June 2020.

The team used the index of multiple deprivation, which divides local areas into five equal groups from the most to the least deprived, to assess the effect of the vaccination program by social and economic deprivation.

Between 1 January 2006 and 30 June 2020 there were 29,968 diagnoses of cervical cancer and 335,228 of grade 3 precancerous cervical lesions (CIN3) in women aged 20–64 years.

In the group of women offered vaccination at age 12–13, rates of cervical cancer and CIN3 in the additional year of follow-up were, respectively, 84% and 94% lower than in the older unvaccinated group. Overall, the researchers estimate that by mid-2020, HPV vaccination had prevented 687 cancers and 23,192 CIN3s. The highest rates remained among women living in the most deprived areas, but the HPV vaccination program had a large effect in all five levels of deprivation.

For example, the greatest numbers of cervical cancer cases were prevented in women in the most deprived areas (192 and 199 for first and second fifths, respectively) and the fewest in women in the least deprived fifth (61 cancers prevented).

The number of women with CIN3 prevented was also high across all deprivation groups but greatest among women living in the more deprived areas: 5,121 and 5,773 for first and second fifths, respectively, compared with 4,173 and 3,309 in the fourth and fifth fifths, respectively.

For women offered catch-up vaccination at age 14–18, CIN3 rates decreased more in those from the least deprived areas than from the most deprived areas. However, for cervical cancer, the strong downward gradient from high to low deprivation seen in the older unvaccinated cohort was no longer present among those offered the vaccine.

This is an observational study so no firm conclusions can be drawn about cause and effect, and individual-level data on vaccination status were not available. However, randomized controlled trials have shown conclusively that the vaccine works in preventing HPV infection and in preventing CIN3 in women free of HPV at the time of vaccination.

What’s more, the authors say this was a well-designed study based on high-quality population-based cancer registry data, making it “powerful and less prone to biases from unobserved confounders than an analysis based on individual-level data on HPV vaccination status.”

As such, they conclude, “The HPV vaccination program in England has not only been associated with a substantial reduction in incidence of cervical neoplasia in targeted cohorts, but also in all socioeconomic groups.”

They add, “Cervical screening strategies for women offered vaccination should carefully consider the differential effect both on rates of disease and on inequalities that are evident among women offered catch-up vaccination.”

The HPV vaccine is key to eliminating cervical cancer inequities, say US researchers in a linked editorial.

They point to the importance of attaining the 90% coverage target recommended by the World Health Organization, but acknowledge several challenges such as vaccine hesitancy, finances, health system capacity, supply, and variation in the extent to which health care providers recommend vaccination.

To overcome the challenges of reaching target coverage and to maximize population herd immunity, “collective efforts of government, community stakeholders, and health care professionals in these countries will be necessary,” they conclude.