Nível de evidência acerca da eficácia das vacinas disponíveis contra a infecção pelo vírus HPV: revisão sistemática

Abstract

Annually, about 500,000 new cases of cervical cancer occur and nearly 230,000 women die worldwide affected by this cancer, with particular emphasis on developing countries. Persistent HPV infection is a necessary condition for the occurrence of this disease and the oncogenic types HPV 16 and HPV 18 are responsible for approximately 70% of cervical cancer cases. In the last decade, prophylactic HPV vaccines have been developed, aimed at reducing the incidence of cervical cancer, with priority given to adolescent girls aged 9 to 15 years old. Currently, there are two commercially available HPV vaccines: Bivalent (HPV 16 and 18) and Quadrivalent (types 6, 11, 16, 18). This study aimed to perform a systematic review on commercially available HPV vaccine efficacy in women, with a focus on evaluation of vaccine efficacy stratified by age groups and outcomes. Six randomized controlled trials were selected of the 378 studies identified in MEDLINE, LILACS and Cochrane Collaboration, corresponding to 41,750 women. The Bivalent and Quadrivalent vaccine significantly reduced the risk of occurrence of precursor lesions of cervical cancer presenting efficacy of 96.9% (95% CI, 90.2-99.0) for CIN2 and 96.2% (CI 95%, 89.0- 98.7) for CIN3 in the per protocol population analysis when compared to the control group. Only one study - MUÑOZ et al (2009) - brought results of HPV vaccine efficacy by age subgroup. Involving 3,819 women of 24-45 years without previous history of infection with the vaccine subtypes (6, 11, 16, 18) on the baseline, enrolled in a randomized multicenter study with the Quadrivalent vaccine, placebo controlled with follow-up period about 26 months. A combined outcome of persistent infection for at least 6 months duration, cervical intraepithelial neoplasia and external genital lesions was used. For the age group of 24-34 years, vaccine efficacy was 91.8% (95% CI, 67.1-99.1) and age 35-45 years was 88.6% (CI 95%, 51.9-98.7). Vaccine efficacy of the entire population enrolled in the protocol was 90.5% (CI 95%, 73.7-97.5). The prophylactic vaccination can prevent HPV infection in women from 15 to 45 years not previously infected with the HPV subtypes covered by the vaccines by at least 5 years, corresponding to the maximum time of follow-up studies included in this review. For evaluation of vaccine efficacy on the incidence and mortality of cervical cancer will be necessary, however, longer follow up studies