Overall, the eight programs included in this study performed very well by the two indicators used. Mean program coverage across all programs was 88% and mean adherence between D3 and D1 was 91%. The highest program vaccination coverage was reported in the Bolivia 1 program. Such a high coverage rate in a school-based model was somewhat unexpected. However, it should be noted that there was a high demand for HPV vaccination from other nearby schools not originally included in the program. The program manager and health authorities extended the vaccination period for an additional two weeks in order to accommodate this demand. Due to the extended time frame and the inclusion of girls from schools not included in the initial targeting plan, the program was able to vaccinate more girls than originally expected, which accounted for a coverage rate greater than 100%.
School-based vaccination delivery methods were most effective at reaching girls within the WHO-recommended age range, which is likely due to the fact that girls aged 9-13
years are not usual “clients” of the health care system. Additionally, few health systems have robust follow-up systems in place for ensuring that participants visit the clinic for each of the three scheduled vaccinations. It should also be noted that the Cambodia project, which used a health facility-based model, was approved prior to the issuance of the WHO age recommendations for HPV vaccination and included girls older than 13
years of age. This certainly contributed to the lower percentage of girls within the age range for health facility-based models compared with the other models.
However, school-based projects faced several challenges when vaccination dates occurred outside of scheduled school days. It was exponentially more difficult to prevent loss to follow-up in these instances and in some cases, clinic and/or door-to-door follow up was necessary to complete the 3 doses.
Interestingly, there was a trend toward increased rates of project coverage and project adherence with an increasing number of vaccine administration sites. This trend makes sense given that more sites increase the capacity for vaccine administration and, in fact, vaccine utilization is higher when administration sites are easily accessible [20
]. However, it was not necessarily a given that small pilot programs such as those described here would have the resources or expertise to successfully manage multiple sites. These results suggest that local organizations can successfully implement relatively larger HPV vaccination campaigns and that additional sites should be considered in order to increase access to and delivery of HPV vaccines.
Mixed models yielded better overall performance (program vaccination coverage and adherence indicators) compared with school or clinic models. This may be due to promotion of the program through health and educational channels. Community participation appeared to be a less effective recruitment driver than channels that utilized schools and clinics. The ability to deliver vaccination at school or a clinic site increased the likelihood that participants would receive their vaccinations on time even in cases of school relocation, family migration or vaccination schedules that coincided with school holidays. Adherence in school-based models may also have been negatively affected by the 2010 earthquake in Haiti, which occurred between D2 and D3 of the school-based Haiti program.
The feasibility and success of a similar mixed model has also recently been demonstrated in Peru [23
]. The data show that inclusion of HPV vaccination did not diminish health facilities’ capacity to administer routine infant vaccination programs. Additionally, an analysis of HPV vaccine acceptability in Botswana found that public or community clinics would be the most common place at which people would get HPV vaccine and that 74% of study participants indicated that they would have their daughters vaccinated against HPV at school if the vaccine was available there[16
]. These findings further support the utility of a mixed model encompassing both school and clinic-based vaccine delivery.
Based on the success and challenges of these eight GAP programs, it is recommended that future programs should conform to local norms for other vaccinations with respect to signed consent by girls and their families who chose to receive HPV vaccination. Additionally, specific resources should be allocated to sensitize and train schoolteachers to assist in recruitment of and follow-up with girls during HPV vaccination campaigns. Such training was deemed an essential component to the success of a school-based HPV vaccine program in Peru [23
]. Teachers and headmasters were also considered decision-makers with respect to school-based HPV vaccination in Peru, Uganda and Vietnam, and schools were identified as effective sources for community health education programs about cervical cancer [11
]. Effective use of schools as venues for HPV vaccine programs has also been identified as an important factor in the successful adoption of HPV vaccine in low-resource settings [19
The high levels of estimated coverage and vaccination adherence achieved with these programs could be due to their relatively small size and close monitoring, and the fact that resources have been allocated to them specifically to conduct HPV vaccination activities. For the current design of the GAP, the analyses of these projects are a measure of the ability of a project or institution to recruit participants and ensure that they receive all 3-vaccine doses. These analyses do not assess the ability of a project or institution to provide HPV vaccine coverage to an entire population. Consequently, the two indicators used to assess programs undertaken are distinct from those related to measuring vaccine coverage.
In addition to a small sample size of only eight programs, this study has several limitations. The use of census data to determine the number of eligible girls within the geographic regions of health facility-based or mixed model programs is an imprecise methodology that could give rise to errors in determining target population. Given that target population is the denominator in the calculation used to determine program vaccine coverage, error in determining the number of eligible girls who could participate in a program will impact coverage rates. This potential for error is somewhat less of an issue in the three programs that used school-based models because school enrolment data is more precise than census data. Although population density could also impact program vaccination coverage, data on population density were not systematically collected and were thus not included in the analysis reported here.
Three programs had program coverage greater than 100%: Bolivia 1 (school-based model), Cambodia (health-facility model), and Nepal (mixed model). It is possible that errors in the census data used to calculate the denominator of the coverage estimation account for these results in the Cambodia and Nepal programs. However, it is also possible that demand for HPV vaccination near to but not within the original coverage area resulted in the recruitment of more girls than expected. Information campaigns and community involvement may have been more effective than expected in some areas or programs, which also could have increased recruitment above original estimates. However, it is also possible that demand for HPV vaccination near to but not within the original coverage area resulted in the recruitment of more girls than expected. Information campaigns and community involvement may have been more effective than expected in some areas or programs, which also could have increased recruitment above original estimates.
Cost analysis data and model projections on cost-effectiveness of different HPV vaccination programs in low- and middle-income countries are not included because the cost data collected were incomplete. Additionally, the projects reported on here are pilots developed at the community level, and may not be applicable to larger regional or national campaigns that may comprise diverse socio-economic, religious, and cultural constituencies. Optional preventive strategies, regional strategies, or mixed strategies in rural low-income regions could play an important role in addressing the challenges associated with HPV vaccine coverage, access, and acceptance [24
]. Data from the projects described here may enable diverse approaches that allow individual countries or regions to maximize the coverage of HPV vaccination campaigns.