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John Halstead

Public health interventions in the 20th century have been responsible for massive improvements in global health. According to the Copenhagen Consensus,

“Life expectancy hardly changed before the late 18th century. Yet it is hard to overstate the magnitude of the improvement since 1900, from a life expectancy of 32 years to 69 now, to 76 in 2050. The biggest factor was the fall in infant mortality.”[1]

68% of the improvement in human health is down to technical improvements, such as vaccines, micronutrient fortification and deworming medicine, while higher income accounts for only 3%. For example, Sub-Saharan Africa’s real per capita income in 2008 was just over half that of England in 1870, and yet child mortality rates are two thirds lower in Africa in 2008 than in England around 1870.[2]

Under five Years of Life Lost (YLL) as a percentage of total YLL 1990 – 2050.[3]

Many critics of aid[4] underestimate the sheer scale of the progress that has been achieved as a result of public health interventions, which are often supported by foreign aid and international bodies such as the World Health Organization (WHO), UNICEF and the World Bank. In this blogpost, I will briefly describe and assess some of the most successful public health interventions of the 20th century.

This research relies to a large extent on the prior work done in this area by the Centre for Global Development, which has been published as Millions Saved. We have selected four of the twenty case studies from Millions Saved, examined the evidence given, and tried to provide reasonable estimates of cost-effectiveness. In addition, we look at an intervention not covered in Millions Saved – reducing tuberculosis in south east Africa.

We have strong reason to believe that that all of the interventions had high impact and very high cost-effectiveness.[5] All of them averted a Disability Adjusted Life Year (DALY)[6] for less than $50, some of them significantly less, with smallpox eradication, for example, saving a life (30-40 years) for $5. For context: the NHS will spend £30,000 to save a Quality-Adjusted Life Year (QALY);[7] and the world’s most effective charities avert a DALY for around $30.[8]

The smallpox eradication campaign (1967-1979) is by some distance the most effective program considered here and is one of the best public health interventions of all time. In 1967, smallpox affected 10-15m people and killed nearly a quarter of them.[9] The eradication campaign, with the help of the WHO, the US government and endemic countries cost only $300m.[10] It has saved at least 50m lives until today and provided enormous non-life-saving health benefits.[11]

Cost per life saved (1967-2014) = $5 per life.

This suggests that the intervention averted a DALY for significantly less than $1. Indeed, the benefits mentioned here do not include non-life-saving health benefits, such as blindness prevented. The eradication of smallpox was a truly extraordinary public health achievement.

2. Guinea worm reduction in Asia and Sub-Saharan Africa

Giving What We Can views interventions against Neglected Tropical Disease (NTDs) as having high cost-effectiveness.[12] One NTD, which until recently blighted much of Africa, is dracunculiasis AKA ‘guinea worm disease’. Guinea worm is contracted by drinking water bearing the guinea worm parasite. The disease is rarely fatal, but it does impose a significant disability and pain burden on those infected. On average, the disease incapacitates people for 8.5 weeks.[13]

In 1986, the WHO passed a resolution to eradicate guinea worm within 10 years.[14] In close collaboration with UNICEF, the US Centres for Disease Control and Prevention (CDC) and the WHO, the Carter Centre led the eradication effort.[15] To reduce the burden of the disease, the campaign encouraged the provision of safe water and water filtering through cloth, health education, surveillance of new cases and case containment.[16]

In 1986, there were around 3.5m cases of guinea worm worldwide. Today, guinea worm is very nearly eliminated, with fewer than 200 reported cases in 2013.[18] We provide the following estimate of cost-effectiveness:

Cost per DALY averted (1986-2004) = $46.20.[19]

According to Givewell, the global program to eradicate guinea worm is ‘one of the success stories of global health’.[20]

In Egypt in 1978 all cause infant mortality was exceptionally high at 100 per 1000 live births, which meant that more than 100,000 infants died every year. At least half of these deaths were diarrhoea associated.[21] In the 1960s, it was discovered that diarrhoea could be treated effectively with a simple combination of salt, sugar and water, called Oral Rehydration Therapy (ORT).[22]

The Egyptian National Control of Diarrheal Disease Project (NCDDP), introduced in 1981, improved case management of diarrhoea through ORT and better feeding, especially breastfeeding.[24]

There is good evidence to show that ORT significantly reduced infant mortality in Egypt. From 1970-77, the reduction in infant mortality attributable to diarrhoea was 4.2%; from 1977-82 it was 7.8%; whereas from 1982-90 – the peak years of the NCDDP – it was 15.9%.[25] The rate of infant diarrhoeal deaths declined faster than the overall rate of infant mortality after the introduction of the NCDDP.

We conservatively estimate that the programme saved 100,000 lives in the 1980s.[26] According to the Centre for Global Development, the program cost $43m. It was funded by USAID and the Egyptian government and with assistance provided by UNICEF and the WHO.[27] So, we estimate that the program saved a life for $43m/100,000.

This is exceptional. According to a paper in the British Medical Journal, ORT saved 50 million lives worldwide in the 20th century.[28]

4. Controlling tuberculosis in south east Africa

In 2012, 8.6m people fell ill with tuberculosis (TB) and 1.3m of them died (including 320,000 deaths from HIV positive people). In Malawi, Tanzania and Mozambique, national tuberculosis control programmes making use of short-course chemotherapy proved a highly cost-effective tool in the battle against TB.

TB is caused by bacteria (Mycobacterium tuberculosis) that most often affect the lungs. It is highly contagious.[29] Efforts to control TB have been significantly setback by the rise of HIV in the 1980s and 90s, as the two infections co-exist in large numbers of people. In the mid 1960s new drugs were discovered which allowed short-course chemotherapy treatment. This was testimony to the wisdom of the British Medical Research Council, which provided long-term support for tuberculosis research.[30]

In the 1980s, short-course chemotherapy was introduced and rapidly expanded in Malawi, Tanzania and Mozambique.[31] In all three countries, the cure rate for short-course chemotherapy ranged from 70% In Mozambique to 87% in Malawi, whereas the average cure rate for standard chemotherapy was 40-50%.[32] Despite the impact of the HIV outbreak on TB death rates, the chemotherapy cure rate remained largely unaffected by the HIV outbreak.[33] According to De Jonghe et al, the average cost-effectiveness of the intervention was:

Cost per year of life saved = <$6< big="">

According to the WHO, an estimated 37m lives were saved by tuberculosis treatment from 2000-2013.[34] As the tuberculosis situation improves in the developed world, it is nonetheless deteriorating in the developing world.[35] We hope that in the future, the poor will be able to afford the same healthcare resources as the rich today.

5. Preventing Iodine Deficiency Disease in China

Iodine Deficiency Disorder (IDD) is the world’s leading, and most easily preventable, cause of mental illness, with around 50m sufferers today.[36] In severe cases, IDD can cause cretinism and in more mild ones causes goitre.

In 1993, 370 million Chinese people lived in IDD endemic areas, which was 40% of the global at-risk population.[37] The economic cost to China is estimated to be $50bn.[38] After becoming aware of the scale of the problem, China launched the National Iodine Deficiency Disorders Elimination Program in 1993. The program made regions aware of the problem of IDD; strengthened the capacity of the salt industry to iodise; improved monitoring of the quality of salt; and banned non-iodised salt.[39] According to Goh, as a result, the rate of goitre (an illness caused by IDD) among children aged 8-10 fell from 20.4% in 1995 to 8.8% in 1999.[40] We have deduced the following cost-effectiveness estimate:

According to The Copenhagen Consensus salt iodisation was the most cost-effective and desirable intervention available to the world in 2012.[41]

The achievements of these public health interventions are enormous. They are all large-scale, national and international programs which have brought massive benefits at very low cost. The focus here has been chiefly historical, but the successes of the past may guide us towards success in the future. Humanity has done a great deal of good. The challenge we now face is to do the most good possible while we can.

Copenhagen Consensus: How much have global problems cost the world?

See William Easterly, The White Man’s Burden : Why the West’s Efforts to Aid the Rest Have Done so Much Ill and so Little Good (New York: Penguin Press, 2006); Dambisa Moyo, Dead Aid : Why Aid Is Not Working and How There Is Another Way for Africa (London: Allen Lane, 2008).

The full report provides a more thorough examination of the evidence.

To determine the number of DALYs lost due to a disease, a weight factor that reflects the severity of the disease on a scale of zero (perfect health) to one (death) is assigned to the disease. See 

Nancy Devlin and David Parkin, “Does NICE Have a Cost-Effectiveness Threshold and What Other Factors Influence Its Decisions? A Binary Choice Analysis,” Health Economics 13, no. 5 (2004): 437–52.

Give Well: a model for cost-effectiveness of interventions

Ruth Levine, Case Studies in Global Health : Millions Saved (Sudbury, Mass; London: Jones and Bartlett, 2007); Frank Fenner et al., 

 1988, 1363, . The individual case study from Millions Saved is available 

Fenner et al., “Smallpox and Its Eradication,” 1365–1366.

[here]( Levine, Case Studies in Global Health; Fenner et al., “Smallpox and Its Eradication,” 1363. The individual case study from Millions Saved is available <a href=).

Giving What We Can: Neglected Tropical Diseases

Ernesto Ruiz-Tiben and Donald R. Hopkins, “Dracunculiasis (Guinea Worm Disease) Eradication,” Advances in Parasitology 61 (2006): 280–282.

“WHO | Dracunculiasis (guinea-Worm Disease),”

“WHO | Dracunculiasis (guinea-Worm Disease).”

For an explanation of how I arrived at this figure, see the full report.

Give Well: Cost-Effectiveness of Guinea-Worm Eradication

. Givewell notes that the cost of completing eradication may be much greater.

M. EI-Rafie et al., “Effect of Diarrhoeal Disease Control on Infant and Childhood Mortality in Egypt: Report from the National Control of Diarrheal Diseases Project,” The Lancet, Originally published as Volume 1, Issue 8685, 335, no. 8685 (February 10, 1990): 334–38, doi:10.1016/0140-6736(90)90616-D.

Miller and Hirschhorn, “The Effect of a National Control of Diarrheal Diseases Program on Mortality.”

EI-Rafie et al., “Effect of Diarrhoeal Disease Control on Infant and Childhood Mortality in Egypt,” 335.

See Miller and Hirschhorn, “The Effect of a National Control of Diarrheal Diseases Program on Mortality”; EI-Rafie et al., “Effect of Diarrhoeal Disease Control on Infant and Childhood Mortality in Egypt.” The CDG case study somewhat misleadingly reports this figure at page 7 of 

 . I have been unable to get my hands on the stated source for the $43m figure. Miller and Hirschhorn say that the grant assistance totalled $32m. See Miller and Hirschhorn, “The Effect of a National Control of Diarrheal Diseases Program on Mortality.”

Eric De Jonghe et al., “Cost-Effectiveness of Chemotherapy for Sputum Smear-Positive Pulmonary Tuberculosis in Malawi, Mozambique and Tanzania,” The International Journal of Health Planning and Management 9, no. 2 (April 1, 1994): 154–155, doi:10.1002/hpm.4740090204.

“WHO | Micronutrient Deficiencies - IDD,” WHO, accessed September 17, 2014, 

http://www.who.int/nutrition/topics/idd/en/

T. Ma, J. Guo, and F. Wang, “The Epidemiology of Iodine-Deficiency Diseases in China,” The American Journal of Clinical Nutrition 57, no. 2 Suppl (February 1993): 264S.

Chor-Ching Goh, “Combating Iodine Deficiency: Lessons from China, Indonesia, and Madagascar,” Food & Nutrition Bulletin 23, no. 3 (September 1, 2002): 280–91.

“Copenhagen Consensus 2012 - Outcome”

 accessed September 17, 2014,. See the assessment paper 

The Best Public Health Interventions of the 20th Century

Hauke Hillebrandt

The Against Malaria Foundation (AMF) has been one of our highly recommended charities for several years now. Our colleagues at Givewell have published an extensive update recently that was generally very favourable and they continue to rank among Givewell’s top charities. You can read more on 

 In this blog post, we give you an update about their efforts that we feel complement Givewell’s report. You can find more general information about AMF on our 

. In our opinion, AMF continues to be one of the most effective charities in the world.

Recent Scientific findings that relate to AMF’s effectiveness

There is some evidence that malaria increases HIV transmission

. In 2006, a paper published in Science showed that people who are HIV positive have shown a spike in HIV viral load during a malaria fever episode

. They found that, a malaria fever can increase HIV viral load by almost one log (10 times) - and stay at an increased level for a duration of up to 6 weeks

. A recent systematic review and meta-analysis found that acute malaria increases HIV viral load by only 0·67 log10 (see 

But does this increase in viral load cause increases the risk of transmitting HIV? According to a recent review, this seems to be the case: malaria may increase HIV transmission in communities with high HIV prevalence, but has no effect in areas with low HIV prevalence

How large is the increase? Early modelling data suggested that in Kenya, since 1980, this disease interaction may have caused 8,500 HIV additional infections (and about 1 million extra malaria episodes due to HIV - this co-infection might also have facilitated the geographic expansion of malaria to areas where HIV prevalence is high)

. Another study showed that individuals who live in areas with high malaria parasite rate have about twice the risk of being HIV positive compared with individuals who live in areas with low malaria parasite rate, after controlling for important socioeconomic and biological factors

. Surprisingly, the cause of the high HIV prevalence in sub-Saharan Africa is not completely understood

. One of the unsolved question was why HIV spread so rapidly in Sub Saharan Africa, even though there is a very low probability of HIV transmission through heterosexual sex, which is commonly assumed to be the main driver of HIV transmission (estimated to be ~ 1/300 per coital act in low income countries, where ulcerative STIs are more prevalent

. Some researchers have suggested that it is high HIV-1 plasma viral loads in sub-Saharan Africa, partly because of high rates of coinfection, may have been one of the drivers of the “explosive” epidemics seen in that region

 modelled the coinfection of HIV with malaria and other diseases such as schistosomiasis. Based on their findings, they argue against the notion that explosive HIV epidemics in sub-Saharan Africa has been driven by higher community viral load due to coinfections. They concluded that duration of coinfection is too short and/or the viral load elevation is too modest to reduce HIV-1 transmission or the duration of asymptomatic HIV-1 infection substantially. The authors estimate that for every 100 HIV-infected people, each suffering 1 episode of malaria infection, there are only 0.4 (2.7th– 97.5th percentile [95% confidence intervals]: 0.0–2.0) to 2.4 (0.0–21.0

) (depending on whether there are multiple infections per year) additional HIV-1 transmission events attributable to HIV-Malaria coinfection. For lymphatic filariasis, which bednets might also offer some protection from (see below), it is 13.3 (0.3–89.2).

In sum, the research on HIV malaria interactions is inconclusive and more research is needed to investigate these interactions. However, independent of the effect size, and whether the coinfections are a/the main driver of the HIV epidemic in subsaharan Africa or not, some authors have argued even a small increase in transmission risk from these cofactors generates large numbers of new HIV infections. Thus, for the present case of estimating the effectiveness of bed net distribution, we believe that there is good reason to assume that net distributions are even more cost-effective than previously assumed - we just do not know by how much at this point. In any case, the full economic cost-benefit analysis includes both the positive effects of malaria prevention, which is high already, plus any additional positive effects on top of this that one gets ‘for free’, even if future research estimate these effects to be small. For people who particularly value disability and morbidity during adulthood as opposed to early childhood morbidity

, this might be a reason for the Against Malaria Foundation becoming more attractive. Some researchers have argued cofactor-related interventions are only hesitantly included into African HIV prevention strategies

 and that among policy makers and donors, however, there is still some resistance to investing in bed nets (and other preventative health interventions), to reduce new HIV infections.

Finally, two recent studies suggest that independent of whether and by how much HIV transmission risk is increased, coinfections might have implications for distribution of malaria nets to people infected with HIV. One study suggested that people with HIV that were provided with bednets had slower progression to AIDS

 and another study showed that people with HIV who were provided nets and water filters delayed initiation of antiretroviral therapy, potentially due to this slower progression to AIDS

. The later study estimated this intervention to be highly cost effective: when combining the benefits due delayed initiation of antiretroviral therapy with other health benefits due to fewer malaria cases, this interventions costs US$99 per disability-adjusted life year (DALY) averted (with net cost savings for the health system). Another recent study found that almost all the HIV positive patients in a sample with malaria infection were anemic

. But can net distribution reduce the morbidity of people who are infected with HIV? A recent review concluded the data were very limited regarding the impact of net provision and/or use on malaria morbidity reduction in people with HIV. The quality of the four studies they reviewed was rated as “medium.”, the overall quality of evidence was rated as “fair”, and and the impact of net provision on malaria morbidity was rated as “uncertain”

. More research needs to be done to investigate this interaction.

1.62 billion people have anemia. 41.8% of all pregnant women have anemia, with the majority living in Africa: 17 million pregnant women are known to be affected

The consequences of malaria-induced anemia in pregnancy has been well established and the impact of distribution of bednets to pregnant women are described in a 2006 Cochrane review

. The evidence shows that sleeping under nets compared to not sleeping under nets increased mean birth weight by 55 g, reduced low birth weight by 23%, and reduced miscarriages/stillbirths by 33% in the first few pregnancies. This strongly suggests that it is a good idea for pregnant women to sleep under nets in Africa

. However, as of 2010, insecticide-treated nets were used during pregnancy for only 10·5 million of 26·9 million births across 37 countries

. Finally, a recent paper showed that there was also a significant association between anemia and asymptomatic malaria among pregnant women.

Another affected group are HIV positive patients: a recent study found that almost all the people in a sample with malaria infection were anemic

. Few studies have looked at the effect of malaria on anemia in non-pregnant, non HIV-infected adults. One study in Cameroon however suggested that in adult patients with fever, malaria parasitaemia contributes to anaemia and that this is of public health impact

. This improves the case that reduction of malaria through net distributions also decreases incidences of anemia.

Synergistic effects of using nets to prevent both malaria and lymphatic filariasis have been investigated for a long time

, as both diseases are transmitted by Anopheles mosquitoes (see Table 1 (adapted from

). A recent paper calls for integrated vector management and concludes that the available data show that the use of treated or untreated bed nets and indoor residual spraying for malaria control concomitantly also reduced lymphatic filariasis

. For this reason, Nigeria has recently launched the first nationwide lymphatic filariasis and malaria co-implementation plan, based on distribution of both preventive chemotherapy medication and long-lasting insecticidal nets

AMF currently plans to carry out all of their future net distributions in Malawi and the DRC. The DRC has one of the highest prevalences of lymphatic filariasis

 and no mass drug administration against it has been carried out hitherto

Malawi also has high prevalence of lymphatic filariasis and and mass drug administration coverage against lymphatic filariasis is incomplete (about 80%)

. One recent study suggests that malaria interventions such as bednet distributions likely have also affected LF transmission

Studies show that treating lymphatic filariasis coinfection in HIV‐positive patients significantly reduced their viral load

. A modelling study estimated that this might increase transmission risk and that for every 100 HIV-infected people, each suffering from lymphatic filariasis, there are 13.3 (0.3–89.2) additional HIV-1 transmission events attributable to HIV-lymphatic filariasis coinfection

One recent study suggests that malaria during pregnancy might affect blood pressure in children and that this might may contribute to the African burden of hypertension, which is higher than in developed countries

 used a more sensitive test for asymptomatic malaria and showed that malaria is more common than previously thought: the prevalence of malaria in the study’s population was underestimated by 8%. Asymptomatic malaria carriers influence the transmission potential of the disease 

. This suggest that the malaria burden might be underestimated.

Another review has recently concluded that the morbidity burden of Malaria has been underestimated in particular with regards to adult morbidity

A recent study suggested that increasing temperatures due to climate change might mean that future climate becomes more suitable for malaria transmission in the tropical highland regions

Evolution of resistance to insecticides continue to worry researchers: resistance in mosquitoes has been reported in 53 of 65 reporting countries around the world since 2010

. However, a recent meta-analysis concluded that ITNs are still more effective than nets that are not treated with insecticides regardless of resistance

 and distributing nets remains a cost-effective health intervention, even in areas with strong insecticide resistance

Does providing free bednets increase the number of people sleeping under bednets?

It has been hypothesized that people who purchase nets will use them more than those who receive them for free and thus that free bednet distributions are not as good as selling them.

 reviewed the evidence on this and suggests that there is probably little or no difference in net use among those who receive a free net compared to those who pay for one. They suggest that providing free insecticide-treated bednets probably increases the number of people who own bednets compared to providing subsidized bednets or bednets offered at full market price

. Another study showed that children who receive their nets through NGOs or government likely receive some education about bednets and are more likely to use them in comparison to those children who receive nets that are bought privately through private health centers, market, shops and street vendors

Two recent studies tried to answer the question of whether providing free bednets affects private net sales negatively. One study showed 34 per cent monthly decline immediately after a free bednet distribution campaign compared to ‘normal’ sales

. They found that after 6 months, the total unsold nets reached 45 percent of normal sales, or 347 000 nets nationwide in Tanzania. They caution that free campaigns can hinder private net sales much more than previously observed in recent experimental trials and thus can cause trouble with continuous coverage delivery channels of bednets through private sales. In contrast, another study also in Tanzania, showed distribution of free insecticide-treated nets do not interfere with continuous net distribution

. The authors argue that the discrepancy between the two studies is likely because they used to different data from different time points. We cannot conclude much from only two studies with opposite findings, but whether free net distributions displace private net sales should be subject of further study and observation.

Two recent papers challenge the previously held assumption that net durability is about 3 years.

Insecticide treated nets with holes in them are less effective at protecting people from malaria than intact nets

. In line with this, monitoring of durability of nets in Rwanda showed greater than anticipated bednet loss, associated with poor fabric integrity, during year two of a three year LLIN distribution-replacement cycle. The proportion of the remaining nets in need of replacement, after two years, was large enough to suggest that the intervention would lose impact during year three of the distribution-replacement cycle

 and this might be one of the reasons for resurgence of malaria in Rwanda in 2009, following a 2006 under-five, country-wide bed net campaign. Similarly, another study suggests that the bednet in distribution conducted every three years, which is a key intervention of Benin’s malaria control strategy, is insufficient and a two-year serviceable life for the current LLIN intervention in Benin would be a more realistic program assumption.

Another recent analysis suggested that because of previously unaccounted factors such as uneven distribution of nets and rapid net loss, it will require substantially more nets than currently assumed in order to meet international coverage targets

. All this suggest that more bednets are probably needed than previously assumed, which is favourable for AMF and their part in trying to close this gap.

 “claimed countless [people in Africa] are not using their mosquito nets as global health experts have intended”, most often for fishing, which causes harm to fish stock due to the nets insecticides and fine gauges. Givewell has already commented on this piece

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