The effectiveness of vaccination to prevent the papillomavirus infection: a systematic review and meta-analysis

Our purpose was to determine the effectiveness and harms of vaccination in patients with any sexual history to prevent the prevalence of papillomavirus infection. A search strategy was conducted in the MEDLINE, CENTRAL, EMBASE and LILACS databases. Searches were also conducted in other databases and unpublished literature. The risk of bias was evaluated with the Cochrane Collaboration's tool. Analysis of fixed effects was conducted. The primary outcome was the infection by any and each human papillomavirus (HPV) genotype, serious adverse effects and short-term adverse effects. The measure of the effect was the risk difference (RD) with a 95% confidence interval (CI). The planned interventions were bivalent vaccine/tetravalent/nonavalent vs. placebo/no intervention/other vaccines. We included 29 studies described in 35 publications. Bivalent HPV vaccine offers protection against HPV16 (RD -0.05, 95% CI -0.098 to -0.0032), HPV18 (RD -0.03, 95% CI -0.062 to -0.0004) and HPV16/18 genotypes (RD of -0.1, 95% CI -0.16 to -0.04). On the other side, tetravalent HPV vaccine offered protection against HPV6 (RD of -0.0500, 95% CI -0.0963 to -0.0230), HPV11 (RD -0.0198, 95% CI -0.0310 to -0.0085). Also, against HPV16 (RD of -0.0608, 95% CI -0.1126 to -0.0091) and HPV18 (RD of -0.0200, 95% CI -0.0408 to -0.0123). There was a reduction in the prevalence of HPV16, 18 and 16/18 genotypes when applying the bivalent vaccine, with no increase in adverse effects. Regarding the tetravalent vaccine, we found a reduction in the prevalence of HPV6, 11, 16 and 18 genotypes, with no increase in adverse effects.