Cervical cancer vaccination indications, efficacy, and side effects

Due to the limited contact of the human papillomavirus (HPV) with the immune system, past infection does not guarantee lasting protection. Two preventive vaccines (Gardasil and Cervarix) that can impede persistent HPV infection and its consequences are now available. They use structural L1 capsular proteins obtained by genetic recombination and antigens for genotypes 16 and 18, which are responsible for around 70% of cases of uterine cancer worldwide. Evaluation of their protective efficacy is based on the capacity of the vaccine to prevent persistent infection and cervical intraepithelial neoplasia (CIN). Phase I and II trials showed the safety of these vaccines and their capacity to produce very-high titers of antibodies (low or non-existent after natural infection). Phase II and III trials have confirmed these aspects and shown an efficacy of nearly 100% in the protocol analysis in preventing infection and the CIN associated with oncogenic vaccine genotypes. Some trials have also shown cross-protection against infections produced by other genotypes (such as 45 and 31). The optimal vaccination strategy is vaccination of girls aged 8-14 years. Other strategies should include the catch-up of adolescent and women not yet sexually-active, as well as the vaccination of sexually-active women. The progressive development of primary prevention strategies should coexist with secondary prevention with redesigned screening programs. The successful development of vaccination programs will require the support of public health authorities, the coordination of health workers from different areas and increased public awareness.