MCMC-Driven mathematical modeling of the impact of HPV vaccine uptake in reducing cervical cancer

Abstract

Human Papillomavirus (HPV) is a group of contagious viruses primarily transmitted through sexual contact and is a major cause of severe health issues, including cervical cancer. In Sub-Saharan Africa, including Tanzania, cervical cancer is the leading cause of cancer-related deaths among women of all ages. In 2022, there were 125,699 new cases and 80,614 deaths, making cervical cancer the second most common cancer. Of these, Tanzania recorded 10,868 cases and 6,832 deaths. To reduce the number of girls and female affected by HPV infections, particularly those vulnerable to cervical cancer, we have developed and analyzed a mathematical model for HPV transmission dynamics that incorporates vaccination. The analysis demonstrates the presence of both HPV-free and endemic equilibrium states. By applying the Graph Theoretic method, the reproduction number $R_e$ was computed. The results indicate that the HPV-free equilibrium is globally asymptotically stable when $R_e\le 1$, while the endemic equilibrium is globally asymptotically stable when $R_e>1$. We employed a Markov Chain Monte Carlo (MCMC) method for model calibration, which highlighted several key factors. The interaction between vaccination rates for young girls and older females suggests long-term benefits from vaccinating both groups, contributing to increased herd immunity. Additionally, the strong identifiability of the recovery rate emphasizes its critical role in reducing HPV prevalence and cervical cancer progression. The correlations observed indicate the dual role of vaccination in both preventing infection and promoting recovery. On the other hand, the poor identifiability of the mortality rate points to gaps in understanding the long-term burden of cervical cancer. However, since the data used are synthetic, the uncertainties highlight how important it is to use real data and break it into groups to better understand how different factors affect the results. The herd immunity threshold was calculated to be 0.4417, recommending that at least 55.83% of the population be vaccinated to halt HPV transmission and reduce cervical cancer incidence.