RAPID HUMAN PAPILLOMAVIRUS (HPV) TESTING VERSUS HPV-16,-18 VACCINATION IN HAITI

Purpose: Invasive cervical cancer is the most frequent cause of cancer death among women in Haiti. While conventional cytology screening has not been feasible, two promising options could soon be accessible: for women over age 35, secondary prevention using rapid HPV testing and same-day treatment, and for girls ages 9-11, primary prevention with vaccination against HPV-16 and -18. Both will require price reductions to be cost-effective. For country-level decision making on cervical cancer prevention, the relative value of each new technology will depend on effectiveness and achievable coverage.  We used an empirically-calibrated simulation model of HPV infection and cervical cancer to estimate the mean reductions in cancer risk and mortality associated with cervical cancer prevention strategies.

Method: Model calibration was conducted using a likelihood-based approach, fitting model outcomes to country- and region-specific epidemiologic data (e.g., age-specific prevalence of HPV and precancerous lesions, HPV type-distribution, and cervical cancer incidence). Face validity of the model was assessed using primary data collected from women in rural Haiti. Analyses were conducted with a random sample of good-fitting parameter sets. Strategies included screening 3 times per lifetime at ages 35, 40 and 45 with rapid HPV testing followed by same-day treatment if needed, vaccination at age 9 prior to sexual debut, and combined screening and vaccination. Vaccine efficacy, achievable vaccination coverage, and achievable screening coverage were varied in sensitivity analysis.

Result: Assuming complete protection against HPV-16,-18 in girls previously unexposed, the mean reduction in lifetime cancer risk was 30% (range 26.4%-39%) with a school-based vaccination program reaching 90% of primary school enrollees (~56% enrollment at age 9). If this strategy included rapid HPV testing in adulthood, reductions would increase to 43% with 25% screening coverage, and 52% with 50% screening coverage. For older girls, vaccine efficacy is likely to be reduced as girls increasingly will have been exposed to HPV infection and school enrollment rates rapidly decline. For example, with a 25% decline in efficacy and a 25% drop-off in school enrollment, vaccinating in the mid-teens would provide a mean reduction of 13.8%.

Conclusion: Even if attainable vaccination and screening coverage rates are low in Haiti, a program of school-aged vaccination and rapid HPV testing 3 times per lifetime in adulthood could cut cervical cancer deaths in half.