A Feasibility Study for the Clinical Trial: "A Scientific Evaluation of One and Two Doses of the Bivalent and Nonavalent Prophylactic HPV Vaccines" (1DT)

Selection of study population and recruitment. Costa Rica is divided in provinces that are further divided in cantons, which are subdivided into districts. Districts are conceptually divided into minimal geo-statistical units (MGUs), territorial units roughly equivalent to a block. These MGUs were defined by the National Institute of Statistics and Census (INEC) for the national census conducted in 2011; digital maps and census data by age and gender for MGUs are available.

The study area being proposed for the 1DT was defined to reach an adequate catchment area in order to fulfill 1DT enrollment goals of 20,000 girls. This defined area includes ~125,000 girls in regions where previous NCI/PEG studies were conducted as well as new provinces.

For the feasibility study, three urban and three rural districts from three different provinces were selected: San Ignacio de Acosta and Tibas in San José; Desamparados and Cirri Sur in Alajuela and, Liberia and San Antonio de Nicoya in Guanacaste. MGUs in these districts will be ordered randomly and the first MGU within the selection will visited. An experienced study outreach worker (OW) will visit all houses within the selected MGU and will enumerate and collect information on all girls ages 12 to 16 residing in the MGU. At that time, if a potentially-eligible girl is present, the OW will invite her to participate in the feasibility study by informing her and her parent/legal guardian of the feasibility study, and if interested, will assign a participant study ID (PID). The informed consent/assent process for the feasibility study will be conducted at that time. Once consented/assented, the girl will be appointed to a medical office close to her house, where she will be expected to attend the feasibility study visit. If a potential participant or her parent/legal guardian is not present, the OW will leave study materials with the household and arrange to return at another time to discuss the study. The brochure will include a phone number in case the girl/parents want to get additional information by phone. Within an MGU, five contact attempts will be made per house. Once all houses in the selected MGU have been visited, if fewer than 15 households of participants have been enrolled, the next random selected MGUs will be visited (note, this is defined as girls in a household instead of individuals girls since girls within a household will likely be correlated in their response rate). If 15 or more households of participants have been enrolled after visiting the originally-selected MGU, then the team will move to the next district. This procedure will be repeated until approximately 15 girls have been enrolled in the district, but once an MGU is selected and visited, all houses in that MGU should be visited before moving to another district, even if more than 15 girls are enrolled, to allow for valid computation of the participation rate.

Data on the number of houses approached, average number of visits necessary to collect information in each house (maximum of five visits), percentage of houses contacted during first visit, subsequent visits, number of houses where it was not possible to obtain information, number with girls in the age range, number of girls potentially eligible as determined during home visit, number which consent and agree to attend a study visit, and the true number of girls who attend the study visit, will be collected.

Feasibility Study Clinic Visits. The guiding principle for the feasibility clinic visit is that it should parallel the clinic visits planned for the 1DT up to the point of randomization (which cannot be mocked in the feasibility study).