Footnotes for "GiveWell donors supported more than direct delivery: AMF and new net research"

[1] See "Bednets" tab, 2019 GiveWell Cost-Effectiveness Analysis — Version 6 (public), cell C81. $100,000/48 = $2,083.33. In other words, we expect one death to be averted for every marginal $2,083 spent on AMF's LLIN distributions.

In general, our cost-effectiveness analyses are simplified models that rely on many difficult judgment calls and inputs for which limited data is available. To reflect the imprecision of the model, we provide a range, rather than a single estimate, and round to the thousands, arriving at the estimated $2,000 to $3,000 we share in the post.

[2] "An insecticide-treated net (ITN) is a net (usually a bed net), designed to block mosquitoes physically, that has been treated with safe, residual insecticide for the purpose of killing and repelling mosquitoes, which carry malaria." (GiveWell, Mass Distribution of Long-Lasting Insecticide-Treated Nets (LLINs), last updated March 2018)

[3] "Insecticide resistance (defined broadly as any ways in which populations of mosquitoes adapt to the presence of insecticide-treated nets (ITNs) in order to make them less effective) is a major threat to the effectiveness of ITNs. Insecticide resistance seems to be fairly common across sub-Saharan Africa, and it seems that resistance is increasing." (GiveWell, Insecticide Resistance and Malaria Control, Last Updated November 2019)

[4] "Our very rough best guess (methodology described in more detail below) is that ITNs are roughly one-third less effective in the areas where the Against Malaria Foundation is working than they would be in the absence of insecticide resistance. ITNs remain a highly cost-effective intervention after incorporating this discount." (GiveWell, Insecticide Resistance and Malaria Control, Last Updated November 2019)

[5] "The implications of current levels of insecticide resistance for the effectiveness of ITNs are unclear. There are no high-quality studies that estimate the impact of insecticide resistance on ITNs’ effectiveness, partly because of ethical restrictions on testing ITNs via new randomized controlled trials (RCTs). Experts generally seem to argue that ITNs remain highly effective in most locations, but this conclusion seems to be based on low-quality information." (GiveWell, Insecticide Resistance and Malaria Control, Last Updated November 2019)

[6] "PBO nets are a newer type of net incorporating piperonyl butoxide (PBO) alongside the standard pyrethroid insecticide used in other nets. PBO is a synergist which inhibits the metabolic enzymes that grant immunity in mosquitoes." (GiveWell, Insecticide Resistance and Malaria Control, Last Updated November 2019)

[7] "In September, 2015, a WHO expert group reviewed the evidence for PBO long-lasting insecticidal nets to define their deployment. Despite awaiting for more conclusive evidence from community randomised controlled trials (RCTs) with epidemiological outcomes, WHO, nevertheless, has recommended a small rollout in specific situations." (Protopopoff et al. 2018, pg. 1579)

[8] "We did a cluster RCT of four groups using a two-by-two factorial design. The RCT started on March 1, 2014. The post-intervention assessment period was initially planned for 18 months (from Jan 1, 2015, to June 30, 2016) and was subsequently extended on our request to the funding agency to 24 months (from Jan 1, 2014, to Dec 31, 2016) to enable further assessment of the PBO long-lasting insecticidal net (figure 1). The study area was Muleba district of the Kagera region in northwest Tanzania, and comprised 40 villages." (Protopopoff et al. 2018, pg. 1579)

[9] "In 2017, WHO granted – on an exceptional basis – a conditional policy recommendation for pyrethroid-PBO ITNs. The recommendation was developed based on findings from one trial in Tanzania and will remain conditional until data from at least one more trial conducted over 2 years have confirmed the enhanced impact on malaria that was demonstrated in the first study." (World Health Organization, New types of insecticide-treated nets, January 15, 2020)

[10] Our assessment relies on the senior members of our research staff who led our investigation into PBOs and AMF.

[11] "AMF plans to fund at least one, and possibly two, studies on insecticide resistance. One of these studies will be conducted by the Liverpool School of Tropical Medicine with the 2015 Nord Ubangi distribution. We have now seen a preliminary research proposal for this study. The study will include:

  • Measurements of species abundance, resistance prevalence and level, and the effect of PBO (an insecticide) on insects’ mortality at baseline and at a 1-year post-distribution follow-up
  • Monthly measurements of insect pesticide resistance in households covered by different net types (some households will be covered by standard LLINs while others will be covered by standard LLINs that have also been treated with PBO)."

(GiveWell, Against Malaria Foundation - May 2015 Update)

[12]

[13]

[14] "The AMF-funded study is being led by the Liverpool School of Tropical Medicine (LSTM) who are working closely with the London School of Hygiene and Tropical Medicine (LSHTM), University of California San Francisco (UCSF) and researchers at the Infectious Diseases Research Collaboration (IDRC) in Kampala and at Makerere University, both of the latter in Uganda…. The study team carried out tests and collected data before nets were distributed, a baseline study, and has collected data in two further stages, at 6 months and 12 months post-distribution of the nets… Another organisation has agreed to fund data collection at 18-months and a further study at 24-months may occur." (Against Malaria Foundation, Update on actions to deal with insecticide resistance in some mosquitoes, 29 June 2018)

[15] See, for example: "With respect to improved malaria control, this has only been demonstrated, to date, for one pyrethroid-PBO net – Olyset® Plus – in one cluster randomized trial conducted in Tanzania. A second study to demonstrate impact in controlling malaria, deploying two pyrethroid-PBO products – Olyset® Plus and PermaNet® 3.0 – is currently underway in Uganda; results will likely be made available for WHO review in 2020." (World Health Organization, New types of insecticide-treated nets, January 15, 2020)

[16] LLIN Evaluation in Uganda Project (LLINEUP) – Impact of long-lasting insecticidal nets with, and without, piperonyl butoxide on malaria indicators in Uganda: study protocol for a cluster-randomised trial, Table 1, "Cumulative number of nets allocated"

[17] "Altogether, 45000 standard long-lasting insecticidal nets and 45000 PBO long-lasting insecticidal nets were distributed in February, 2015." (Protopopoff et al. 2018, pg. 1580)

[18] "AMF is very pleased that the research concluded on time, on budget and gained additional support from DFID [the U.K. Department for International Development] (for the 18 month results) and The Gates Foundation (for the 24 month results to come)." (Against Malaria Foundation, PBO Net Trial Results Released (to 18 months), November 21, 2019)

[19] "Delivering LLINs to all people who need them in the 35 countries for which data is available between 2018 and 2020 would cost about $2.75 billion over three years. About $2.1 billion of this is already financed, or is expected to be financed with high confidence, leaving a gap of about $640 million." (GiveWell, Estimating the Funding Gaps for Distribution of Antimalarial Nets and Seasonal Malaria Chemoprevention, November 2018)

[20] Against Malaria Foundation, PBO Net Trial Results Released (to 18 months), November 21, 2019.

[21] "The results show that both conventional [standard] nets and PBO nets reduced malaria prevalence. PBO nets were more effective, both at killing mosquitoes and at reducing malaria in the population. Specifically, after 6 months (of usage) PBO nets were 26% more effective at reducing malaria, after 12 months 27% better, and after 18 months 16% better." (Against Malaria Foundation, PBO Net Trial Results Released (to 18 months), November 21, 2019).

[22] The Gates Foundation has agreed to fund a follow up at 24 months: "AMF is very pleased that the research concluded on time, on budget and gained additional support from DFID (for the 18 month results) and The Gates Foundation (for the 24 month results to come)." (Against Malaria Foundation, PBO Net Trial Results Released (to 18 months), November 21, 2019).

[23] Peter Sherratt, Executive Chairman, Against Malaria Foundation, comments on a draft of the blog post, April 8, 2020 (unpublished).


Source URL: https://www.givewell.org/sources/blog-post/PBO-nets-2020