We estimate that only about a fifth of children at risk of stable malaria transmission were protected by an ITN in 2007. Conversely, nearly 90 million African children living under conditions of stable malaria transmission have been neglected by the calls for rapid scaling up of ITN coverage made by the Roll Back Malaria movement in 2000.32
This neglect comes at a time when these same agencies and international partners are calling for elimination33
and a malaria-free world.34
A large proportion of these unprotected children live in some of the poorest parts of Africa, but the differences in ITN use between spatially defined areas of least and most poor seem less obvious than has been reported before intervention coverage was scaled up (). The procurement of more than 60 million long-lasting treated nets35
and the reports of rapid scaling up of ITN delivery in a few select countries have been hailed as a clear indication of progress toward Roll Back Malaria and Millennium Development Goals' targets.5,6
Reports of sales figures or percentage coverage changes from selective examples mask underlying inequities in ITN use on a continental scale, adjusted for actual populations at risk of developing malaria.
Almost 25 years have elapsed since the first clinical trials of ITN were completed in Africa and more than 10 years since large-scale clinical trial evidence was provided on the contribution of ITN as a major method to reduce childhood mortality across most malaria-endemic settings in Africa. Why then is coverage so poor in 2007? An analysis of international donor funding in relation to populations exposed to stable transmission highlights huge disparities and inadequacies in malaria funding across Africa,2
which must contribute to inabilities to scale up coverage. Some controversy remains about the best approaches to ITN delivery.36,37
In this report, we have shown that the areas of Africa that have promoted free ITN distribution () have overall achieved more rapid progress than those that rely on cost recovery (21% lower median coverage) or routine subsidised public-sector promotion (11% lower median coverage). Fortunately, increasing numbers of countries are complementing existing delivery strategies with free distributions as national or localised strategies after the period of observations reported here, and current ITN coverage in these countries might be higher than our projected estimates.
In some cases, biological vulnerability has scaled up with differences in ITN use within a country, notably Angola, Eritrea, Kenya, Madagascar, and Zambia, and less strategically elsewhere, notably Sudan. National ITN coverage was less than 15% in 2007 in 13 countries, including seven countries (Nigeria, Demographic Republic of Congo, Uganda, Sudan, Mozambique, Côte d'Ivoire, and Cameroon) that account for 53·5 million (48·6%) of all children (110 million) in Africa living under conditions of stable malaria transmission and 48·3 million (54%) of all unprotected children (89·6 million) in these transmission areas. Nigeria alone accounts for 22·2 million (25%) of all African children (89·6 million) living under conditions of stable malaria transmission who were not protected by an ITN in 2007. A focus of attention on these areas in Africa must be seen as a priority if health effects at the continental level are to be realised by 2015.
Such approaches to mapping intervention coverage and risk come with caveats and opportunities for improvement. We have attempted to standardise the ITN coverage to 1 year (2007) of assessment using subnational resolution estimates of ITN use growth rates. For the most part, this process required minor extrapolations, but in a few countries these estimates would have been affected by the timing of the follow-up surveys (). More regular survey data corresponding to changes in delivery modalities is central for improvement of the precision of such temporal interpolation. Additionally, standardised information on coverage of other vector control strategies, such as indoor residual spraying, needs to be generated at the same resolution as ITN to measure the combined effect of these complementary strategies. To generate this information, we need more investment in measurement of progress than is currently available to countries and should be redressed if international agencies are serious about an analysis of whether money is spent where it should be to achieve the intended goals.38
The available evidence suggests that ITNs are similarly effective under a wide range of transmission intensities in averting new infections,22
but the subsequent public-health effect varies,39
and deaths and disease events averted will be highest in communities exposed to high transmission. To assess the public-health impact with changes in ITN coverage will require a more detailed mapping of malaria risk and the effect of seasonality on ITN use at a continental scale. Although not presently available, this work is ongoing as part of the Malaria Atlas Project40
and will provide a more informed map of biological risk with which to plan and assess resource allocation.
Definition of vulnerability and unmet need is central to effective investment strategies by the donor community. Mapping risks, target populations, vulnerability, and coverage provides a means to redress deficiencies in the international calls for 80% coverage of ITN by 2015. These targets remain elusive across vast areas of Africa. Increased funding and more informed use of this funding is desperately needed to protect more children in the most vulnerable and most populated areas of Africa.