The efficacy and duration of vaccine protection against human papillomavirus: a systematic review and meta-analysis

BACKGROUND: The German Standing Committee on Vaccination (STIKO) recommends vaccination against human papillomaviruses (HPV) of the high-risk types 16 and 18. The duration of protection afforded by HPV vaccines has been reported in multiple studies to date but has not been systematically evaluated.

METHOD: Systematic literature review and meta-analysis on the efficacy of vaccination, with assessment of evidence by the GRADE criteria (Grading of Recommendations Assessment, Development and Evaluation).

RESULTS: 15 studies were identified: 10 randomized controlled trials (RCTs) and 5 observational studies. The RCTs included a total of 46 436 participants. The duration of follow-up was short (median, 3 years) in 8 RCTs and long (median, 6 years) in 2 RCTs. During the period of short-term follow up, the pooled efficacy of vaccination for the study endpoint of incident HPV infection (percentage of infections prevented) was 83% (95% confidence interval [CI]: 70-90% ), while the pooled efficacy against persistent HPV infection was 90% (95% CI: 79-95% ). In this period, CIN 2+ lesions were prevented with 84% efficacy (95% CI: 50-95% ), and CIN 3+ lesions with 94% efficacy (95% CI: 83-98% ). During the period of long-term follow-up, incident infections were prevented with 94% efficacy (95% CI: 80-98% ) and persistent infections with 95% efficacy (95% CI: 84-99% ). The long-term efficacy against CIN 2+ lesions was 86% (95% CI: -166-99% ). No data are available on the long-term efficacy of vaccination against CIN 3+ lesions.

CONCLUSION: Long-term observation does not indicate any loss of antiviral protection after vaccination against HPV 16 and 18, although the evidence for long-term protection is of lesser quality than that for short-term protection.