Synergizing Health Strategies: Exploring the Interplay of Treatment and Vaccination in an Age-Structured Malaria Model

Malaria remains a persistent global challenge, particularly prevalent in tropical regions of Africa, Asia, and South America. According to the World Health Organization's (WHO) World Malaria Report 2023, there were approximately 249 million reported malaria cases in 2022 across 85 endemic countries, resulting in over half a million deaths. Progress towards global malaria eradication through antimalarial drugs has been slow, with case numbers increasing since 2015. Dihydroartemisinin (DHA), artesunate, and artemether, derivatives of artemisinin, are crucial components of modern antimalarial treatment. However, resistance to these drugs and their partners in Artemisinin Combination Therapy (ACT) has emerged in Southeast Asia, Africa, and South America. In 2021, the WHO recommended widespread use of the RTS,S malaria vaccine among children in endemic regions. To address these challenges, we develop an extended SEIR age-structured model incorporating malaria vaccination for children, drug-sensitive and drug-resistant strains, and interactions between human hosts and mosquitoes. Our research focuses on evaluating how malaria vaccination coverage influences disease prevalence and transmission dynamics. We derive the basic, intervention, and invasion reproduction numbers for both strains and conduct sensitivity analysis to identify key parameters affecting infection prevalence. Our findings reveal that model outcomes are primarily influenced by scale factors that reduce transmission and natural recovery rates for the resistant strain, as well as by drug treatment and vaccination efficacies, and mosquito death rates. Numerical simulations indicate that while treatment reduces the malaria disease burden, it also increases the proportion of drug-resistant cases. Conversely, higher vaccination efficacy correlates with lower infection cases for both strains. These results suggest that a synergistic approach, involving both vaccination and treatment, could effectively decrease the overall proportion of the population that is infected.