The lower end of the range assumes that the number of children who are malnourished in a year is the same as the number of children who are malnourished at one point in time (and the same children become ill throughout the year). The number of children who are malnourished at one point in time is estimated on the basis of the global population of children under 5 and malnutrition prevalence data, from United Nations World Population Prospects and UNICEF, WHO, World Bank, "Levels and trends in child malnutrition," 2021.
The upper bound estimate assumes children don’t relapse, and it’s always different children who fall ill. So we estimate the number of children who are ill in a year as being the same as the number of malnutrition episodes in a year. We estimate the number of episodes in a year by multiplying the number of children who are malnourished at one point in time by a “correction factor” that accounts for the duration of a malnutrition episode. (We use the estimate in Isanaka et al. 2021.)
See our estimates here.
 "Acute malnutrition is a major public health issue in low-income countries. It includes both wasting and edematous malnutrition, but the terms wasting and acute malnutrition are often used interchangeably." Frison, Checchi, and Kerac 2015, Abstract.
"Wasting refers to a child who is too thin for his or her height. Wasting is the result of recent rapid weight loss or the failure to gain weight." UNICEF, WHO, World Bank, "Joint child malnutrition estimates — levels and trends," 2020, pg. 2.
"In children aged 6–59 months, moderate acute malnutrition is defined as moderate wasting (i.e. weight-for-height between –3 and –2 Z-scores of the WHO Child Growth Standards median) and/or mid-upper-arm circumference (MUAC) greater or equal to 115 mm and less than 125 mm." WHO, "Supplementary foods for the management of moderate acute malnutrition in children aged 6–59 months," 2019.
"Severe acute malnutrition (SAM) is defined as a weight-for-height measurement of 70% or more below the median, or three SD [standard deviations] or more below the mean National Centre for Health Statistics reference values (that will likely be replaced by new WHO growth curves), which is called "wasted"; the presence of bilateral pitting oedema of nutritional origin, which is called "oedematous malnutrition" or a mid-upper-arm circumference of less than 110 mm in children age 1–5 years." Collins et al. 2006, pg. 1.
 Our estimate is based on Olofin et al. 2013, which pools results from 10 longitudinal studies, including five randomized controlled trials (RCTs) of vitamin A supplementation and five prospective cohort studies that recruited participants in the 1970s, 1980s, and 1990s. We apply a number of adjustments to that estimate, including adjustments for confounding factors (i.e., factors that raise mortality risk and are associated with malnutrition, but are not addressed by malnutrition treatment, e.g., geographic remoteness) and adjustments for deaths not being truly averted due to relapse. See here for details.
“Wasting is a life-threatening condition attributable to poor nutrient intake and/or disease. Characterized by a rapid deterioration in nutritional status over a short period of time, children suffering from wasting have weakened immunity, increasing their risk of death due to greater frequency and severity of common infection, particularly when severe”, UNICEF, "Child Nutrition," 2019.
All-cause hazard ratios (HR) for SAM (i.e., weight-for-length z-score < -3)=11.6 (95% CI: 9.84, 13.76). Olofin et al. 2013, Pg. 5, Table 3. Cause-specific HR for respiratory tract infections=9.68 (6.07, 15.43); Diarrheal disease = 12.33 (9.18,16.57); Other infectious causes = 11.21 (5.91, 21.27); Malaria=1.24 (0.17, 9.29); and Measles = 9.63 (5.15, 18.01). Olofin et al. 2013, Pg. 8, Table 5.
 “Evidence does suggest, however, that episodes of wasting negatively affect linear growth and, therefore, undermine child growth and development” UNICEF, WHO, and World Food Programme, "Wasting Policy Brief," 2014, Pg. 2.
 "Children who are identified as having severe acute malnutrition should first be assessed with a full clinical examination to confirm whether they have medical complications and whether they have an appetite. Children who have appetite (pass the appetite test) and are clinically well and alert should be treated as outpatients. Children who have medical complications, severe oedema (+++), or poor appetite (fail the appetite test), or present with one or more Integrated Management of Childhood Illness (IMCI) danger signs should be treated as inpatients (strong recommendation, low quality evidence).” WHO, "Management of severe acute malnutrition in infants and children."
 "Ready-to-use Therapeutic Food (RUTF) has revolutionized the treatment of severe malnutrition – providing foods that are safe to use at home and ensure rapid weight gain in severely malnourished children. The advantage of RUTF is that it is a ready-to-use paste which does not need to be mixed with water, thereby avoiding the risk of bacterial proliferation in case of accidental contamination. The product, which is based on peanut butter mixed with dried skimmed milk and vitamins and minerals, can be consumed directly by the child and provides sufficient nutrient intake for complete recovery." WHO, "Malnutrition."
 “Children with severe acute malnutrition may be more susceptible to infection. . . . WHO recommendations: Children who are 6-59 months of age with uncomplicated severe acute malnutrition, not requiring to be admitted and who are managed as outpatients, should be given a course of oral antibiotic, such as amoxicillin.” WHO, "Use of antibiotics in the outpatient management of children 6-59 months of age with severe acute malnutrition," 2019.
 "Community health workers or volunteers can easily identify the children affected by severe acute malnutrition using simple coloured plastic strips that are designed to measure mid-upper arm circumference (MUAC). In children aged 6-59 months, a MUAC less than 110 mm indicates severe acute malnutrition, which requires urgent treatment. Community health workers can also be trained to recognize nutritional oedema of the feet, another sign of this condition." WHO, "Community-based management of severe acute malnutrition," 2007, Pgs. 2-3.
 Acute malnutrition is a partially seasonal problem, and tends to increase during “lean seasons,” periods between planting and harvesting during which food availability is low. See, for instance: “The prevalence of undernutrition (BMI and/or MUAC), increased significantly during the lean season (from 19.6 to 27.2%) and the incidence of undernutrition between the two seasons was high (12.2%).” Ravaoarisoa et al. 2019, Pg. 6.
 "In order to ensure that children have access to treatment, ALIMA adapts its strategy to the local context based on the needs of the population, the role of the Ministry of Health, and the presence of other NGOs. In addition to directly treating malnourished children, ALIMA engages in some or all of the following activities, depending on the context:
- Conducting training and coaching for Ministry of Health staff
- Hiring and training new staff
- Training caregivers in identifying malnutrition by measuring children’s mid-upper arm circumference (MUAC)
- Determining the level of acute malnutrition, especially among displaced populations
- Supporting the referral system
- Supporting screening at the community level by community health workers
- Improving water and sanitation as well as infection prevention and control
- Raising awareness about malnutrition and feeding practices among caregivers"
 This is estimated on the basis of the under-5 population in sub-Saharan Africa and malnutrition prevalence data, from UNICEF, WHO, World Bank, "Levels and trends in child malnutrition," 2021, and United Nations World Population Prospects. See here for calculations.
 The lower end of the range assumes that the number of children who are malnourished in a year is the same as the number of children who are malnourished at one point in time (and the same children become ill throughout the year).
The upper bound estimate assumes children don’t relapse, and it’s always different children who fall ill. So we estimate the number of children who are ill in a year as being the same as the number of malnutrition episodes in a year. We estimate the number of episodes in a year by multiplying the number of children who are malnourished at one point in time by a “correction factor” that accounts for the duration of a malnutrition episode. (We use the estimate in Isanaka et al. 2021.) See here for calculations.
 The lower bound uses the lower bound estimate of malnourished children and UNICEF’s estimate that two-thirds of severely malnourished children in Western and Central Africa are untreated (which we assume holds across the continent, and for less severely malnourished children). See here for calculations and sources.
The upper bound uses the upper bound estimate of malnourished children. We then estimate children treated on the basis of UNICEF’s estimate that 5 million children were treated in 2020 and that about 75% of severely malnourished children treated in 2020 were treated in SSA (which we assume holds true for later years, and across both severely and moderately malnourished children).
For our calculations and sources, see here.
"The two major features driving cost efficiency in this analysis are the density of children in need of treatment in a health center’s catchment area and the capacity of the national health system." International Rescue Committee, "Cost Efficiency Analysis: Treating Severe Acute Malnutrition," 2016, Pg. 1.
 These studies compare mortality rates of malnourished and non-malnourished children before treatment of acute malnutrition was an established practice. Olofin et al. 2013, for example, pools results from studies that recruited participants in the 1970s, 1980s, and 1990s (see Table 1 for a list of included studies).