The changing nature of HPV associated with high grade cervical lesions in vaccinated populations, a retrospective study of over 1700 cases in Scotland

Assessing real world vaccine effectiveness: A review of Scotland's approach to monitoring human papillomavirus (HPV) vaccine impact on HPV infection and cervical disease

High-risk human papillomavirus (HPV) infections can progress to cervical cancer which is the fourth most common cancer in women globally. In Scotland, the incidence of cervical cancer has a strong socioeconomic deprivation gradient disproportionately affecting women from more deprived areas. An HPV vaccination programme was initiated in Scotland in 2008 targeting girls aged 12-13 years with a catch-up campaign running for the first three years for girls aged up to 18 years. The programme has evolved over the last 16 years with changes in the type of vaccine, dosing schedules and the extension of the programme to boys and gay, bisexual and other men who have sex with men. Vaccine uptake in Scotland has historically been high but has gradually decreased over time and disparities exist in women from more deprived areas of Scotland. The ability to link national immunisation and screening databases in Scotland has allowed direct monitoring of the impact of the HPV vaccine on virological and histological outcomes. Analyses of this linked data have demonstrated real-world evidence of high vaccine effectiveness against HPV infection, cervical disease, and cervical cancer with evidence of herd immunity in unvaccinated women. Continued monitoring is crucial to assess the duration of protection, the impact of vaccine and dosing schedules changes and the emergence of potential type replacement. With the World Health Organisation's aim to eliminate cervical cancer as a public health problem by the next century addressing the inequalities in cervical cancer incidence will be crucial. This will require targeted interventions for women most at risk of cervical cancer to ensure elimination is achieved timely for all women in Scotland.

Update on Effects of the Prophylactic HPV Vaccines on HPV Type Prevalence and Cervical Pathology

Most national prophylactic HPV vaccination programs started in approximately 2008, with either the bivalent Cervarix HPV16/18 or quadrivalent Gardasil (HPV6/11/16/18) vaccines, which were then followed by introduction of the nonavalent Gardasil 9 (HPV6/11/16/18/ 31/33/45/52/58) vaccine from 2015. Since that time, these products have demonstrated their ability to prevent infection with vaccine-covered HPV types and subsequent development of HPV-related cervical and genital pathologies. The data indicate that vaccination of young girls prior to sexual debut is more effective than vaccination of older HPV+ve women. Although some studies have shown a decline in the prevalence of vaccine-covered HPV types, there are national and regional differences in overall vaccine efficacy. Furthermore, several recently published studies show an increase in the prevalence of non-vaccine-covered HPV types in vaccinated populations, which is indicative of HPV type-replacement. It is also notable that vaccine-related changes in HPV type prevalence spread between vaccinated and unvaccinated women at the same geographical location-presumably via sexual transmission. In conclusion, it is not yet clear what effect dissemination of vaccine-associated changes in HPV type prevalence will have on vaccine efficacy and cervical pathology, particularly in mixed populations of vaccinated and unvaccinated women. However, it is very clear these observations do underscore the need for long-term continuation of cervical screening combined with regular reassessment of testing practices.

Invasive cervical cancer incidence following bivalent human papillomavirus vaccination: a population-based observational study of age at immunization, dose, and deprivation

BACKGROUND

High-risk human papillomavirus causes cervical cancer. Vaccines have been developed that significantly reduce the incidence of preinvasive and invasive disease. This population-based observational study used linked screening, immunization, and cancer registry data from Scotland to assess the influence of age, number of doses, and deprivation on the incidence of invasive disease following administration of the bivalent vaccine.

METHODS

Data for women born between January 1, 1988, and June 5, 1996, were extracted from the Scottish cervical cancer screening system in July 2020 and linked to cancer registry, immunization, and deprivation data. Incidence of invasive cervical cancer per 100 000 person-years and vaccine effectiveness were correlated with vaccination status, age at vaccination, and deprivation; Kaplan Meier curves were calculated.

RESULTS

No cases of invasive cancer were recorded in women immunized at 12 or 13 years of age irrespective of the number of doses. Women vaccinated at 14 to 22 years of age and given 3 doses of the bivalent vaccine showed a significant reduction in incidence compared with all unvaccinated women (3.2/100 000 [95% confidence interval (CI) = 2.1 to 4.6] vs 8.4 [95% CI = 7.2 to 9.6]). Unadjusted incidence was significantly higher in women from most deprived (Scottish Index of Multiple Deprivation 1) than least deprived (Scottish Index of Multiple Deprivation 5) areas (10.1/100 000 [95% CI = 7.8 to 12.8] vs 3.9 [95% CI = 2.6 to 5.7]). Women from the most deprived areas showed a significant reduction in incidence following 3 doses of vaccine (13.1/100 000 [95% CI = 9.95 to 16.9] vs 2.29 [95% CI = 0.62 to 5.86]).

CONCLUSION

Our findings confirm that the bivalent vaccine prevents the development of invasive cervical cancer and that even 1 or 2 doses 1 month apart confer benefit if given at 12-13 years of age. At older ages, 3 doses are required for statistically significant vaccine effectiveness. Women from more deprived areas benefit more from vaccination than those from less deprived areas.