Takeaway
- Routine immunisation of girls aged 12-13 years using the bivalent human papillomavirus (HPV) vaccine in Scotland against high-grade cervical disease was found to be highly effective.
- In unvaccinated women, reduction in disease was evident, possibly because of herd protection.
Why this matters
- Findings emphasise the credibility of using high-risk HPV infection as an early marker of the effectiveness of the vaccine and reinforce the recent call for global action on cervical cancer from the World Health Organization.
Study design
- This retrospective study included 138,692 women born between 1988 and 1996 and who had a smear test result recorded at age 20 years.
- Effect of routine immunisation with the bivalent HPV vaccine on levels of cytological abnormalities and cervical intra-epithelial neoplasia (CIN) was assessed.
- Funding: No external funding.
Key results
- Vaccinated women born in 1995 and 1996 vs unvaccinated women born in 1988 demonstrated:
- 89% reduction (95% CI, 81%-94%) in prevalent CIN grade 3 or worse from 0.59% to 0.06%;
- 88% reduction (95% CI, 83%-92%) in CIN grade 2 or worse from 1.44% to 0.17%;
- 79% reduction (95% CI, 69%-86%) in CIN grade 1 from 0.69% to 0.15%.
- Vaccine effectiveness for women vaccinated at age 12-13 years vs those vaccinated at age 17 years was:
- CIN grade 1 (78% [95% CI, 66%-86%] vs 41% [95% CI, 14%-59%]);
- CIN grade 2 (89% [95% CI, 81%-94%] vs 56% [95% CI, 35%-70%]);
- CIN grade 3 or worse (86% [95% CI, 75%-92%] vs 45% [95% CI, 17%-64%]).
- Herd protection against high-grade cervical disease was observed in unvaccinated girls in the 1995 and 1996 cohorts.
Limitations
- Analysis was confined to women attending cervical screening at age 20 years.
- Short follow-up period.
References
References
