Estimates of the total economic cost show that, per year, the IRS operationalization cost is US$117,351.34 on average. In the financial analysis, the average cost totaled US$69,174.83. Furthermore, this study revealed that the main components drivers of the cost of IRS in both settings are vehicles, salaries and insecticides costs, accounting for 52%, 17%, and 13% of the total economic cost and 21%, 27%, and 22% in the financial analysis.
In this current study, the economic cost per person protected was estimated to be US$4.34 in Matutuíne and US$3.84 in Namaacha, and the financial cost per person protected was estimated to be US$2.93 and US$1.99 in Matutuíne and Namaacha, respectively. Although the application of costs analysis received considerable attention in evaluating costs of implementing malaria interventions, it is important to recognize that, to date, few cases of single cost analysis for IRS have been drawn up. In developing countries, most of the few available data are relatively old [25–27]. These studies estimated that the financial and economic costs per person protected ranged between US$0.86 and US$3.48. To illustrate, the study which was done in the highlands of Kenya, found that the financial cost for protecting one person by IRS was US$0.86, while the economic cost was US$0.88 . The study in southern Mozambique found that the economic cost per person protected per year by using IRS in rural areas was US$3.48 and US$2.16 in peri-urban areas, while the financial cost for rural areas was US$3.86 and US$2.41 for peri-urban areas . The study in KwaZulu‐Natal, South Africa, found cost per person protected by IRS was estimated in US$1,42 . Several factors could be considered in compering these cost disparities. For example, the lower costs presented in these studies compared to the present study, could be due to the insecticides used. Have been reported that in early 2000s within several Africa countries were primarily using DDT due to the low cost and longer residual decay rates compared to other insecticides . However, at this time, in Mozambique, DDT was shifted to a considerable costly insecticide, carbamate bendiocarb, for IRS until 2005 [6,8]. Thus, this difference on the insecticide used may have influence the high estimates in the current study and in the study in southern Mozambique. Additionally, the analysis of combined interventions in the study done in Kenya that focused on the analysis of a combined malaria intervention of IRS and the distribution of long-lasting insecticidal bed nets, which can generate cost savings .
Thus, this may reduce personal costs for each intervention and would plausibly result in lower costs overall. The other factor to consider is how these costs might differ by country-specific characteristics and the conditions of intervention adoption. Heterogeneities in factors such as target region and population size could have impacted transport and logistical costs. On the other hand, assuming the use of 2014 data, the results of the current study should not be interpreted as conservative estimates as recent studies done in Africa and other settings have been also presenting similar results. For example, a cost-effectiveness of a combined intervention of long-lasting insecticide-treated bed nets and IRS spraying in Ethiopia, and found the unit cost of malaria prevention with IRS alone per person protected was US$3.07 . Programmatic analyses done in Mozambique in 2014, show that cost per person protected in was US$ 2.26 . The report that estimated the resources needed to implement the Health Sector Strategic Plan (PESS) for the period of 2014–2019, found that IRS operationalization began the third malaria intervention control with the highest unit costs (US$2) .
This study aims to offer an important contribution to the government of Mozambique, by providing evidence of the magnitude of IRS operationalization costs, to shed light on concerns about budget constraints. With the NMCP’s intention of scaling up IRS and other vector control interventions to target at least 85% coverage of the population by 2022, evidence shows major players of IRS financing are external, guaranteeing funds for vehicles and insecticides all corresponding to a share of the total combined average costs of 65% (vehicles, 52% and insecticides, 13%) of the total economic cost and 43% (vehicles, 21% and insecticides, 22%) of the financial analysis.
The cost of vehicles was approximately US$61,440 on average, corresponding to 52% and 21% of the total average economic and financial costs respectively. In this analysis, decreasing vehicle costs by 25% reduced the average economic cost by 13%, from US$117,351.34 to US$101,990.66. On the other hand, in relation to the average financial cost, when vehicle costs decreased by 25%, the average financial cost decreased from US$69,174.83 to approximately US$66,371.71, showing a change of approximately 5%. These results show that vehicle costs do not influence the financial analysis of IRS operationalization much. In fact, one observation of this study is that district health directorates have traditionally operationalized IRS using donated vehicles to reach the targeted households. Instead, the cost of insecticides was approximately US$16,000 on average, corresponding to 13% and 22% of the total average economic and financial costs, respectively, making this the second cost driver in the financial analysis.
As the results show, donor contributions currently guaranteed funds for IRS insecticides, insecticide commodities, and vehicles, meaning that no cash expenditure or financing from the national government budget was used to purchase these items. However, in the context of budget restrictions and high dependence on external resources, it is also important to consider the impact of the COVID-19 pandemic and the consequence on the sustainability of critical public health programmes, as it causes high-level expenditure and has dominated priorities in the political agendas of governments, particularly in the global health sector. This has led to prioritization of resource allocation and making governments have to deal with challenges to poll resources that are constrained to respond to the pandemic, which can lead to malaria programmes being left without financial resources as has already been reported, and so increasing scepticism that investment in malaria control can be neglected [30, 31, 32]. Thus, the government of Mozambique should be aware of the impact of COVID-19, as those external funds that are allocated to malaria programmes may be shifted to sustain COVID-19 costs.
Personnel salaries which were allocated from the government budget to the district health directorate in the year of analysis were the largest cost driver in the financial analysis, sharing 27% of the total average financial costs. In this analysis, the cost components that comprised personnel salaries were as follows: recruitment and selection (US$521), training (US$6,000), social mobilization (US$970), supervision (US$213), and IRS delivery by spray operators (US$19,300). Meaning that, the personnel salaries cost was mostly driven by costs of spray operators, followed by the cost of training. On the other hand, the sensitivity analysis shows that after reducing this cost by 25%, the average economic cost decreased by approximately 4%, from US$117,351.34 to US$112,461.68, and the average financial cost decreased by approximately 7%, from US$69,174.83 to US$64,285.17. Considering personnel salaries as the main cost driver of the financial analysis and spray operators’ costs as the driver of personnel salary, it is important
also to note that largely due to the reduction in ODA funding, it has been documented that recurrent spending in the health sector has been reduced which has been inconsistent and declining since 2014 . Thus, a suggestion to reduce costs could be if for example spray operators are effectively utilized, some of the operational cost items can be eliminated from the cost of operation for IRS implementation, hence lowering the financial resources needed. In Mozambique, new spray operators are hired for every IRS campaign on a seasonal basis (in accordance with the IRS length); this included costs of recruitment and selection, as well as malaria surveillance and entomological costs. One suggestion is to keep the same spray operators at least while the same insecticides are used in the regions, assuming that no training for the introduction of new insecticides would be needed; this would thus reduce the costs of recruitment, selection, and training that together made up 9% of the total average financial costs. Further cost-reduction strategies involve options such as the use of Community Health Workers as spray operators, ensuring that IRS operationalization is incorporated into their day-to-day activities. This can eliminate or greatly minimize the cost of personnel salaries as the cost of recruitment, selection, and training can be avoided.
Understanding how IRS timing affects the effectiveness of the intervention can further increase impact and would help optimize the deployment of this intervention under budget constraints. Based on the results, and thus, for optimizing IRS operationalization within the available budget, the government of Mozambique should consider continuing targeted spraying, taking into consideration the correct timing for IRS operationalization. It was reported that during the 2014 IRS cycle period in Matutuíne and Namaacha, the spraying round should have been initiated in October during the wet season, and so prior to peak vector abundance; however, the cycle was initiated in December, which corresponds to the peak in vector abundance . Evidence has demonstrated the efficacy of IRS when considering the correct sequential timing and seasonality of the disease . The evidence showed that earlier spraying is related to more effective results in reducing malaria prevalence [25,32–34].
The collection of cost data was the most likely source of information bias in this study. For instance, some information and data regarding intervention costs (specifically material and supplies) were not found in the setting of analysis, thus it was exported from the SPS in Maputo Province. Therefore, data was assumed to be correct and the information was used for both settings of analysis. However, our estimates may be conservative as this information may, therefore, be subject to biases that may have influenced the study estimates. To minimize this bias, source documentation for key data, namely accounting spreadsheets, was reviewed for quality.
The other limitation that this study faced was that it takes into consideration settings that had the government budget as the main source of financing for IRS operationalization activities. The fact that the source of funding has been restricted by ODA may influence the reduction of resources to spend during IRS operationalization. In some instances, the SPS reported constant cuts on the planned activities for the 2014 IRS operationalization due to lack of budget. However, additional factors affecting costs need also be considered in extrapolating these results to other settings.
Additionally, the lack of cost analysis of IRS studies in Africa setting included Mozambique constituted also a limitation for the present study. As such, it was difficult to compare the findings of the study to other studies. This shows a gap in the literature regarding full and single cost analysis of IRS studies to inform decision makers regarding the costs of this important intervention to control malaria. This highlights the urgent need for research to address this shortfall. Thus, based on this evidence, further works in the line of this study are suggested.