Increase of non-vaccine human papillomavirus types in a group of HPV-vaccinated Mexican women. Evidence of Pathogenic Strain Replacement

High risk HPV infection is the etiological factor of Cervical Cancer (CC) and other types of cancer of epithelial origin. HPV 16 and 18 infections are associated with 70% of CC worldwide. At the present time, there is a vaccine that prevents this infections. In Mexico, the HPV vaccine was introduced in 2009. Even if the current vaccine is effective, some models indicate a possible scenario of Vaccine-induced Pathogen Strain Replacement (VPSR). In this report, we performed the molecular detection of HPV in a group of HPV-vaccinated Mexican women to explore a putative scenario of VPSR. We used biological samples from women who went for their routine Pap. The study included eighteen women older than 18 years of age and HPV-vaccinated. As the number of cases analyzed is relatively small, we supplemented the study with an agent-based direct computer simulation. The outcome of the numerical experiments and the analyzed cases complement each other and show that in three different scenarios, there is an increase in HPV cases approx 10 years after vaccination of the first cohort of women. The prevalence of non-vaccine HPV types increases when compared to prevalence of vaccine HPV types. This result could be interpreted as the phenomenon of Vaccine-induced Pathogenic Strain Replacement.