Human Papillomavirus (HPV) Vaccination in Barretos (Pio XII Foundation - Barretos Cancer Hospital)
Condition: Human Papillomavirus; Infection
MeSH terms: Infections
Study type: Observational

Summary: 
      PROJECT JUSTIFICATION: Cervical cancer is a serious public health problem in Brazil, and is
      the cause of significant morbidity and mortality among Brazilian women. In spite of
      government efforts to improve the coverage rates of Pap tests, the disease-related incidence
      and mortality rates remain high and the diagnosis is still too late.Considering that the
      chronic human papillomavirus (HPV) related genital infection leads to cervical cancer
      development, cervical cancer should be the target of primary prevention through vaccination.

      PROJECT OBJECTIVES: This project aims to evaluate de following vaccination indicators: 1)
      Program acceptance rate; 2) Vaccine coverage rate; 3) Three-dose completion rate; 4) Rescue
      vaccination demand; 5) Adverse event rate;

      TARGET POPULATION: Schoolgirls attending the 6th and 7th grades of elementary school (mean
      age = 11.9 yo).

      VACCINATION PROGRAM: The program adopted the quadrivalent vaccine because it is considered
      superior to the bivalent vaccine in preventing HPV-induced lesions. In addition to preventing
      the development of pre-cancer lesions and cervical cancer, the quadrivalent vaccine has also
      proved to be effective in preventing condyloma, and vaginal and vulvar cancer. The girls
      received the vaccines doses at their schools (school-based program) and also at the Barretos
      Cancer Hospital.

      RESULTS:

      Program acceptance rate = 91.8% (95%CI: 87.0%-96.8%);

      Vaccine coverage for 1st, 2nd and 3rd doses = 87.5% (95%CI: 82.9%-92.2%), 86.3% (95%CI:
      81.8%-91.1%) and 85.0% (95%CI: 80.5%-89.7%).

      Three dose completion rate = 97.2% (95%CI: 92.0%-100.0%). Reasons for dropping out of the
      vaccination program included: moving out of town (17), lost during follow up (16), guardians'
      decision but without a reasonable justification (3), girl refused to continue in the program
      (1) and pregnancy (2). Two girls interrupted the vaccination because of adverse events
      reported by the parents.

      Rescue vaccination demand = 279 girls on the first dose (20.3%; 95%CI: 17.9%-22.8%), 357 on
      the second dose (26.3%; 95%CI=23.6%-29.1%) and 291 on the third dose (21.7%;
      95%CI=19.3%-24.4%).

      Thirty adverse events were recorded or observed in 4,074 doses, providing an adverse event
      rate of 0.7% (95%CI: 0.5%-1.1%). There was no severe adverse event.
    


Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The study included young girls enrolled in public and private schoolgirls, attending the
        6th and 7th grades of the elementary school. Pregnant and breastfeeding adolescents and
        girls who did not attend classes (although enrolled at school) were excluded. Considering
        the inclusion criteria, 19 schools were candidates to the project (13 public and 6
        private). The list provided by each school accounted for 1,615 girls, out of which, 41 were
        not eligible for the study. Thus, 1,574 girls were considered as potential candidates to
        the vaccination program.
      
Keywords: HPV infection; Cervical cancer; HPV vaccine