Swedish registry study: HPV vaccination almost eliminates cervical cancer when given before 17
Among 1.7 million Swedish girls and women, quadrivalent HPV vaccination cut invasive cervical cancer by 88% when given before age 17 and by about half when given at 17-30.
A nationwide cohort of 1,672,983 girls and women aged 10-30 was followed from 2006 to 2017 through Swedish registries, linking HPV vaccination status to invasive cervical cancer diagnoses. Analyses adjusted for age, calendar year, county and parental characteristics.
Cumulative incidence of cervical cancer by age 30 was 47 per 100,000 in vaccinated women and 94 per 100,000 in unvaccinated women. The adjusted incidence rate ratio was 0.12 for women vaccinated before 17 and 0.47 for those vaccinated at 17-30.
This was the first population-level demonstration that HPV vaccination prevents invasive cancer, not just precancerous lesions.
- Adjusted incidence rate ratio for cervical cancer 0.37 (95% CI 0.21-0.57) overall in vaccinated vs unvaccinated
- Vaccinated before age 17: IRR 0.12 (95% CI 0.00-0.34), an 88% reduction
- Vaccinated at 17-30: IRR 0.47 (95% CI 0.27-0.75)
- Cumulative incidence by age 30: 47 vs 94 per 100,000
Vaccinating girls before they are exposed to HPV prevents most cervical cancers. Catch-up vaccination in young adults still helps, but less. Combined with HPV screening, elimination of cervical cancer as a public health problem is a realistic goal.
- Observational; residual confounding by health-seeking behaviour is possible despite adjustment
- Follow-up ends at age 30, before most cervical cancers occur
- Sweden used the quadrivalent vaccine; effects for bivalent and nonavalent vaccines are inferred
- Does not address single-dose schedules or vaccination of boys