Estimating the impact of the RTS,S/AS01 malaria vaccine in Benin: A mathematical modelling study

BackgroundMalaria constitutes a major public health burden in sub-Saharan Africa. It remains a key health concern and the leading cause of death in children under five years of age in Benin. Since October 2021, the World Health Organization has recommended the use of malaria vaccines for the prevention of Plasmodium falciparum malaria in children living in malaria endemic areas, prioritizing areas of moderate and high transmission in sub-Saharan Africa. However, with the exception of Ghana, there is a scarcity of studies modelling the potential impact of the RTS,S/AS01 vaccine in the context of West Africa. This study addresses a gap in research by modelling the impact of malaria childhood vaccination on Plasmodium falciparum malaria transmission in Benin. MethodsA compartmental mathematical model has been developed to estimate clinical and severe malaria cases averted in children under the age of five with the primary series (3 doses) of the RTS,S/AS01 malaria vaccine in Benin. Over a period of 10 years, scenarios including vaccine introduction at different coverage levels to supplement the use of long-lasting insecticidal nets to assess the impact of the RTS,S/AS01 vaccine on malaria transmission in Benin are modelled. ResultsThe model projected malaria burden alleviation by malaria vaccination in Benin. The combination of childhood malaria vaccination at a coverage equivalent to the national DTP3 coverage and the current use of long-lasting insecticidal nets is projected to result in 40% reduction in malaria clinical cases and deaths among children under five years old compared to using nets alone, from 2025 to 2034. However, if the introduction of a malaria vaccine has the unintended consequence of decreased net use, cumulative benefits may be offset. A 1.5-fold decrease in the use of long-lasting insecticidal nets is projected to result in an increase in malaria burden, surpassing baseline levels despite the introduction of the vaccine. ConclusionThis modelling exercise concludes that childhood vaccination is expected to avert clinical and severe cases of malaria and is an additional tool to advance malaria control efforts in Benin but potential unintended consequences of a reduction in net usage may reduce these gains.