Could the human papillomavirus vaccine prevent recurrence of ano-genital warts?: a systematic review and meta-analysis

Human papillomavirus (HPV) is the most prevalent sexually transmitted infection worldwide and ano-genital warts (AGWs) are highly infectious. This virus is transmitted through sexual, anal, or oral contact as well as skin-to-skin contacts. Treatment for this condition has significant morbidity and it can be frustrating in certain cases. The HPV vaccination has been demonstrated as a promising strategy of secondary prevention in HPV-related diseases such as head and neck cancers, cervical diseases, and recurrent respiratory papillomatosis. Regarding AGWs, it is unclear whether vaccination can provide analogous clinical benefit. The aim of this work is to systematically review the literature regarding HPV vaccination for secondary disease prevention after treatment of AGWs. From October to December 2018, a systematic search for clinical trials was conducted in five databases: PubMed, MEDLINE, EMBASE, Cochrane, and clinicaltrials.gov using a combination of the following descriptors: 'gardasil' OR 'cervarix' OR 'nine-valent' OR '9-valent' OR 'vaccine' AND 'recurrence' OR 'relapse' AND 'hpv' OR 'papillomavirus' AND 'warts' OR 'condyloma.' Data were synthetized and entered in the Review Manager software (RevMan 5.3.5) to perform the meta-analysis. The search yielded 824 potentially relevant studies. Two studies fulfilled the eligibility criteria involving 656 participants. The meta-analysis estimated the rate of recurrence of AGWs was similar between the vaccine group and the control group. The overall effect estimate was 1.02 (0.75-1.38). This is the first meta-analysis exploring the effect of HPV vaccine in preventing the relapse of AGWs. These results suggest that HPV vaccination does not provide secondary benefit in patients with previous AGWs. However, these results cannot be generalized due to the scarce number of RCTs currently available in the literature. The outcomes from future randomized controlled trials (RCTs) are warranted to further clarify the precise effect of the vaccine.