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School of Mathematical Sciences

Cost-effective malaria interventions: Using mathematical modelling to save lives

Malaria interventions map
Jamie Griffin

Dr Jamie Griffin

Lecturer in Applied Probability

By evaluating the cost and benefits of new and existing malaria interventions, Dr Griffin’s research has saved as many as 87,000 lives in Africa.

Malaria kills over 440,000 people per year. Over 80 per cent of malaria deaths occur in Africa, making the continent a priority for research and policy efforts.

Several effective interventions for malaria exist, including drugs and insecticide-treated bed nets (LLINs). But knowing which interventions will achieve the biggest impact on malaria cases and deaths is important for making decisions on where to direct funding.

By revealing the most cost-effective interventions to combat malaria, Dr Jamie Griffin and collaborators advised the Global Fund on where to allocate their funding. The Global Fund is a leading global partnership that works to combat malaria and provides 65 percent of all international funding to this goal.

By following Griffin and colleagues’ advice, the Fund’s activities were able to reduce new malaria cases by up to 27 million.

New hope for eradication

Dr Griffin applies his mathematical modelling expertise to a range of scientific questions, from understanding how malaria is transmitted from person to person to the effectiveness of different malaria interventions.

The reproduction number of a disease, R0, is the average number of new cases that arise from a single case. First developed over 60 years ago to explain malaria transmission, the concept has since been applied to many diseases, including most recently coronavirus, and has guided public health responses to the pandemic.

Many simple modelling studies have suggested that malaria eradication is out of reach, as the disease can persist indefinitely even in its R0 is below one. However, Dr Griffin’s modelling work found that immunity can reduce the onward infectiousness of malaria, indicating that if interventions were able to reduce R0 to below one for long enough, local eradication could be possible.

Addressing a knowledge gap  

Griffin and his collaborators then looked to address which interventions are the most cost-effective to control malaria and potentially move countries closer towards eradication.

Previous studies had proved the effectiveness of interventions such as insecticide-treated bed nets in reducing malaria deaths, however the cost-effectiveness of these measures remained unknown.

With new and emerging interventions such as malaria vaccines on the horizon, Griffin and colleagues wanted to compare the costs and benefits of introducing new interventions like vaccines with the scaling up of existing measures.

Dr Griffin and his co-workers combined models of malaria transmission with real-world data from experimental studies and clinical trials in sub-Saharan Africa to assess the cost-effectiveness of four different interventions (bed nets, house spraying, seasonal drugs and the vaccine). In the absence of World Health Organisation (WHO) guidelines to support funding allocations, this work filled a vital knowledge gap for organisations like the Global Fund.

This work enabled us to understand how to target funding in the absence of external guidance, in a way that would otherwise have been impossible.
— Scott Filler, Leader of the Malaria Team at the Global fund

What did the researchers find?

Interestingly, the research revealed that bed nets are the most cost-effective intervention to prevent malaria infection. Where transmission of malaria is seasonal, the next most cost-effective measure was found to be drug treatment, but in other situations the second most cost-effective option was house spraying with insecticide.

The vaccine is considerably more expensive than other interventions, so only becomes cost-effective once high coverage of the other three interventions has been achieved. However, in areas were malaria transmission is very low, or very high, the vaccine ends up more cost-effective, with cost-effectiveness close to bed nets.

Making informed choices 

Dr Griffin’s work enabled the Global Fund to strategically allocate around 4 billion US dollars in funding across sub-Saharan Africa in 2017-2019, at a time where WHO advice on whether to fund new interventions or scale-up existing measures did not exist.

By following Griffin and colleagues’ recommendations and scaling up coverage of bed nets (by 197,000,000 nets) and house spraying (by 12,500,000 structures), the Global Fund is estimated to have saved as many as 87,000 lives and reduced the number of malaria cases by up to 27 million.

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