The potential impacts of the COVID-19 crisis on maternal and child undernutrition in low and middle income countries

The COVID-19-related economic crisis and food- and health-system disruptions threaten to exacerbate undernutrition in low- and middle-income countries (LMIC). We used three modelling tools (MIRAGRODEP, Lives Saved Tool, and Optima Nutrition Tool) to estimate impacts on child stunting, wasting, and mortality, maternal anemia, children born to low BMI women, and future productivity losses for three scenarios across 2020–2022 (n = 118 LMICs). We also estimated the additional cost of mitigation for six nutrition interventions to maximize non-stunted and alive children. By 2022 COVID-19 could result in an additional 9.3 million wasted and 2.6 million stunted children, 168,000 additional child-deaths 2.1 million maternal anemia cases, 2.1 million children born to low BMI women and US$29.7 billion future productivity losses due to excess stunting and child mortality. An additional $1.2 billion per year is needed to mitigate these effects. Governments and donors must maintain nutrition as a priority, continue to support resilient systems, and ensure ecient use of new and existing resources.


Introduction
Before COVID-19, the world was already off-track to achieve the Sustainable Development Goal 2 to eliminate hunger and all forms of malnutrition by 2030. 1 The COVID-19 pandemic and related global economic recession are a severe setback to already insu cient progress towards the global nutrition targets for stunting, wasting, maternal anemia, and breastfeeding by 2025. 1 Pandemic-related economic contractions and food and health systems disruptions now threaten to exacerbate maternal and child undernutrition across low-and middleincome countries (LMIC). 2 Measuring the effects of the COVID-19 disruptions on delivery of essential health and nutrition interventions has proven challenging as resilient real time information systems were not well established in many countries prior to the crisis. The World Health Organization (WHO) Pulse Survey reported health service disruptions between March and June 2020 in 90% of the 105 countries surveyed across ve regions. More than half of the surveyed countries documented disruptions in antenatal care, sick child services, and management of malnutrition and 70% of countries reported disruptions in routine immunization. 3 Experience from previous pandemics suggests that health system recovery could be slow; after the 2014 Ebola outbreak in West Africa it took more than one year for health care services to fully recover. 4 Evidence on the economic and food insecurity impacts of COVID-19 is also emerging. Global estimates from mid 2020 -prior to further deteriorations in economic growth forecasts -suggested that economic contractions and food supply chain disruptions have contributed to increased household food insecurity and 95 million people falling into severe poverty. 5,6 Updated projections suggests 150 million people will become poor in 2020. 7 Evidence from targeted phone surveys in Asia and Africa also points to disturbingly large increases in poverty and food insecurity throughout 2020. 8,9,10,11 Disruptions in supply chains for perishable nutrient-rich foods such as fruits and vegetables and animal source foods have been reported at local levels, especially during lockdowns, leading to price volatility and declining consumption of these foods. 6,12 As a coping strategy poor households facing income losses tend to shift to cheap sources of calories including starchy staples, cereals, oils, and/or non-perishable ultra-processed foods and reduce consumption of nutrient-rich fruit and vegetables and animal source foods such as dairy, meat, and sh. 13,14,11 These dietary changes likely lead to poorer quality diets, which in turn can increase the risks of undernutrition, and especially micronutrient de ciencies. Social protection programs, including cash and food transfers and school meals were disrupted early in the pandemic 15 and, although many countries have adapted, modi ed, or scaled up their programs, 16,17 they are likely to fall short of needs.
Early insights on the disruptions to economic, food and health systems suggest a range of potential implications for nutrition. There have been separate estimates of the impacts of health system shocks on child wasting and maternal and child mortality 18, 19 and of the economic shocks on poverty in the early stages of the pandemic. 9,10,11,12 However, to date there is no comprehensive assessment of the combined effects of economic, food and health systems disruptions on multiple forms of maternal and child undernutrition.
We have aimed to ll this gap by using several modelling tools to present a multi-year picture of the potential consequences of the economic, food and health systems crises triggered by COVID-19 for maternal and child undernutrition in 118 LMICs. We estimated the potential impacts for 2020-2022 of the crisis on: 1) child stunting, wasting, and mortality, maternal anemia and children born to women with low body mass index (BMI); and 2) associated human productivity losses. Mitigating the impact of these disruptions requires extra nancial resources, and so we also estimated the effects of COVID-19 on the domestic and donor nancing landscape for nutrition, the additional costs of interventions to mitigate the rise in maternal and child undernutrition, and the effects of optimizing budget allocations for nutrition.

Results
Maternal and child undernutrition and child mortality Child wasting: Compared to projections without COVID-19, the moderate scenario estimates an additional 9.3 million children under ve with wasting (WHZ<-2 SD) from 2020 to 2022, based on predicted GNI declines in the 118 countries (6.4 million in optimistic; 13.6 million in pessimistic) ( Table 2). Two-thirds of these additional wasted children in the moderate scenario would be in South Asia (6.2 million) and 1.9 million in sub-Saharan Africa.
Child stunting: Under the moderate scenario, an estimated 2.6 million additional children will be stunted in 2022 compared to 2019 due to interruptions in nutrition services and declines in household poverty status. (1.5 million in optimistic; 3.6 million in pessimistic) ( Table 2). Almost 1.2 million would be in Sub-Saharan Africa and 790,00 in South Asia (Web Annex 1). Under 5 mortality: Under the moderate scenario, there will be an estimated 168,000 additional under 5 deaths in the 118 countries over the three years due to predicted increases in child wasting and declines in nutrition intervention coverage (47.000 in optimistic; 283,000 in pessimistic) ( Table 2). Consistent with wasting, most of these additional deaths are in South Asia and Sub-Saharan Africa (Web Annex 1). However, under the optimistic scenario, a 10% increase in the treatment of moderate acute malnutrition in 2022 relative to 2019, would contribute to 61,000 "lives saved" in 2022 and reduced net 47,000 deaths over the three years (Table 2).
Maternal anemia and low BMI: The moderate scenario estimates an additional 2.1 million pregnant women with any anemia in the 118 countries in 2020-2022 compared to 2019 (1.0 million in optimistic; 4.8 million in pessimistic) ( Table 2). Also an additional 2.1 million children would be born to women with low BMI in 2020-2022 (1.4 million in optimistic; 3.0 million in pessimistic scenario) (Web Annex).
Adverse birth outcomes: Two maternal nutrition interventions introduced in the optimistic scenario in 2022 have a positive impact on small-forgestational-age (SGA) and preterm births and stillbirths: MMS in place of IFA, and balanced energy protein supplementation for malnourished pregnant women. An increase to 10% coverage in 2022 would prevent an estimated 400,000 cases of SGA, 296,000 preterm births and 7,600 stillbirths across the 118 countries.

Future productivity losses
The estimated additional burden of childhood stunting and child mortality would result in future productivity losses between the ages of 18 and 65 years (using country-speci c life expectancy) of $14.9 billion, $29.7 billion, and $44.3 billion under the optimistic, moderate, and pessimistic scenarios, respectively. Additional cases of anemia during pregnancy would result in $79 million in lost productivity between 2020-2022 ($36 for optimistic -$177 million for pessimistic) (Figure 1). Across the three outcomes, these losses represent between 0.1% and 0.3% of current GNI in the sample of 118 countries.

Financing landscape for nutrition
Since 2002, ODA to nutrition-speci c and nutrition-sensitive sectors has on average trended with donor country economic cycles, but with a lag. We ran regressions with GDP growth lags of up to ve years, but only the two-year lag is ever statistically signi cant (always with an elasticity slightly greater than 1). Therefore, like Stuckler et al. (2011), our results are reported with lags of up to two years. For every percentage point increase in national growth there is typically a 1.6 percentage point increase in ODA two years later. For domestic nancing, for each one percentage point increase in growth there is a 1.5 percentage point increase in domestic health expenditure, with no time lag. Using the MIRAGRODEP moderate scenario, our dynamic model implies that ODA to nutrition will decline slightly through 2021 before the lagged effect fully manifests in 2022 with a decline of 8.9%. In this scenario ODA does not recover to pre-crisis levels until 2028. Domestic nancing for health (including nutrition-speci c nancing) is projected to fall by 7.2% in 2020, 4.2% in 2021, and 2.2% in 2022, not recovering to pre-crisis levels until the end of the decade unless there is strong recovery in economic growth in LMICs. Relative to no-COVID projections all three disruption scenarios project a signi cant ODA shortfall to nutrition-relevant sectors through 2030 (19% in pessimistic; 14% in moderate; 9% in optimistic), accompanied by a similar decrease in domestic health budget (Web-Annex).
Additional nancing needs and optimizing existing nancing Based on the projected increases in stunting, wasting, and anemia during pregnancy under the moderate scenario, we estimate an additional $1.2 billion per annum ($763 million in optimistic; $1.7 billion in pessimistic) will be needed to mitigate the impacts of COVID-19 on maternal and child undernutrition (Table 3). Scaling up nutrition interventions with direct and indirect effects on child mortality will also avert additional child deaths.
Improvements in allocative e ciency of six nutrition interventions ( Figure 2) could avert some of the indirect effects of COVID-19 on nutrition. Our multi-country analysis suggests that realigning nancing from provision of complementary foods towards a more targeted and balanced mix of interventions could lead to as many as 8.2 million (4.9%) fewer stunted children under ve in 2022 and 339,000 (2.2%) under-ve deaths averted in 2020-2022 compared to a scenario without optimization ( Figure 2). The illustrative intervention mix includes an expansion of SAM treatment and infant and young child feeding (IYCF) counselling for children 6-23 months of age in food-secure populations, combined with provision of complementary foods in food-insecure populations, increases in vitamin A supplementation, breastfeeding promotion and balanced energy-protein supplementation to women with a low BMI.

Discussion
Our projections demonstrate that, regardless of the scenario, the COVID-19 crisis is expected to have dramatic effects on maternal and child undernutrition and child mortality in the current generation, with massive long-term negative consequences on productivity. The impacts of COVID-19 on health and food systems disruptions, and especially the global economic recession it has triggered, will likely continue at least until the end of 2022 and will jeopardize the efforts of both LMICs and donors to achieve the global nutrition targets and SDGs 2 and 3.
If we focus on the moderate scenario used in our analyses, the changes in GNI per capita due to the COVID-19 crisis could result in an additional 9.3 million wasted children between 2020-2022, a large increase relative to the 47 million wasted children reported in 2019. 20 Reductions in coverage of nutrition services and increases in household food insecurity could add 2.6 million stunted children by 2022 to the estimated 144 million stunted children in 2019. After two decades of global decline in stunting, this would effectively reverse the last year or two of progress. Together these increases in child undernutrition and drops in coverage of essential nutrition services could lead to an estimated 168,000 additional deaths in children under ve by 2022. Future productivity losses attributable to increased child stunting and mortality are US$ 29.7 billion, thereby impacting national economies.
Our estimates for increased stunting may be conservative. The rst reason is that we only estimated stunting for children under 5 years of age for the nal year (2022) of our projections in order to avoid double counting due to the progressive and cumulative nature of child stunting. Our estimates, therefore, exclude additional stunting cases that developed in 2020-22, but were older than 5 years of age in 2022. Second, the projected increases in maternal anemia (2.1 million cases by 2022) and children born to low BMI women (3 million by 2022) suggest that our estimates for increased stunting may further increase beyond 2022, as poor maternal nutritional status is a major risk factor for adverse birth outcomes and subsequent child malnutrition. 21 The projected deterioration in nutritional status, child mortality, and lost productivity is sobering and demands immediate cross-sector action. The optimistic scenario signals the potential for the health sector to mitigate short-and long-term negative impacts by focusing on rapidly recovering and even modestly expanding coverage of essential maternal and child nutrition services, including the management and treatment of MAM. The optimistic scenario further suggests that this crisis could be used as an opportunity to accelerate introduction and scale-up of two maternal nutrition interventions -multiple micronutrient supplements (MMS) in place of IFA and balanced energy-protein supplements for low BMI women.
UN agencies have speci cally called for provision of MMS to pregnant women to ensure adequate micronutrient intakes during the COVID-19 crisis. 22 We have an example of using a crisis to scale-up a "new" intervention in the introduction of Multiple Micronutrient Powder (MNP) during the Tsunami response in Aceh, Indonesia in 2006. 23 Similarly, with promising evidence that small-quantity lipid nutrient supplements may improve growth 24 and reduce the risk of child mortality 25 , countries could consider introducing these supplements as part of COVID-19 response strategies.
Our costing and optimisation estimates illustrate that allocative e ciency gains can be achieved using existing resources. It is notable that breastfeeding promotion (which reduces mortality) and complementary feeding (which reduces stunting) could also act as double duty actions to also reduce obesity and micronutrient de ciencies. 26 Further improvements may be possible through technical e ciency gains, such as reducing the cost of SAM treatment or, as noted previously, switching from IFA to MMS during pregnancy. However, our ndings should not be interpreted as prescriptive at the country level. The optimal results and allocative e ciency gains will vary across countries depending on demographics, epidemiological factors, baseline intervention coverages, and context-speci c costs, priority targets, delivery platforms and other constraints. Countries need customised analyses to help decide how to deliver more nutrition for the money available.
To mitigate the effects of COVID-19 on child stunting, child wasting and maternal anemia alone, we estimated that at least an additional $762 million to $1.7 billion per annum will be needed to achieve the global nutrition targets on top of the additional $7 billion per annum estimated in 2017. Previous evidence shows that prior to COVID-19, ODA ows towards nutrition-speci c and nutrition-sensitive sectors were already signi cantly below recommended levels of donor nancing. 1 Our results offer only a conservative estimate given that they are restricted to child wasting and stunting and maternal anemia, and cover only six nutrition-speci c interventions using pre-COVID-19 cost assumptions. Critically, policies and interventions that address the economic and food systems drivers of nutrition are just as important as those that address health determinants. 27,28 Panel 1 proposes a set of critical actions across health, food and social protection systems that countries should prioritize to mitigate the potentially devastating impacts of the COVID-19 pandemic on maternal and child nutrition.
It is reassuring to see that governments have indeed begun to implement various mitigation and adaptation measures to ensure safe delivery of essential nutrition services, to maintain adequate food supply, and to offset losses in income and widespread food insecurity. Examples of strategies that countries have adopted to prevent interruption of essential health and nutrition services include use of digital health technologies, mobile medical teams or campaigns (e.g. vaccination campaigns), task shifting and additional training of staff, home delivery of food and supplements, transport/ nancial support to patients, and strengthening of community outreach networks, among others 3,29 . To maintain an adequate food supply, countries are exploring interventions to improve short to medium term agricultural production 30,31 while programs working with small and medium enterprises (SMEs) have supported the adaptation of marketing, sales and distribution strategies as a result of disruptions in value chains. 29 To mitigate the impacts of the economic crisis on income losses and food insecurity, governments have implemented, adapted, or scaled up social safety net programs including cash and food transfers in more than 200 countries. 16,32,33 However, little information is available on the e ciency and effectiveness of mitigation measures in health, food, and social protection systems. Moreover, it is likely that they these interventions stretch government budgets, fail to meet the overwhelming need for these interventions given the devastating impact of COVID-19 on poverty levels, and leave many of the most vulnerable behind, including women, migrant or refugee populations, and the ultra-poor, to name a few. 34 Our analyses have some limitations. First, uncertainty is present in all modelling exercises. Pessimistic and optimistic scenarios were developed to re ect this, but the models do not account for the different trajectories that national and subnational economic, health and food systems may take depending on differences between countries in current and new waves of infection and/or mitigation efforts. Second, the paucity of pre-COVID baseline data across LMICs on dietary intake, micronutrient status and obesity precluded modelling the effects on the pandemic on all forms of malnutrition. However, the reported disruptions in supply chains for perishable nutrient-rich foods and related drops in availability, affordability, and consumption 35 suggest potentially large impacts on micronutrient de ciencies and rising obesity. 36 In conclusion, the COVID-19 pandemic has created a nutritional crisis in LMICs. Without swift and strategic responses by subnational, national, regional, and international actors, COVID-19 will reverse years of progress and exacerbate disparities in disease, malnutrition, and mortality, and jeopardize human capital development and economic growth for the next generation. 37 We must act now to strengthen the delivery of policies and direct and indirect nutrition interventions across health-food-and social protection systems, both in the immediate and longer-term.
Additional ODA and domestic funding, as well as better use of existing resources, will be critical to mitigate the damage from COVID-19 and reinvigorate efforts to achieve global targets and safeguard good nutrition for all, now and in the future.

Estimating effects on maternal and child undernutrition and child mortality
In order to estimate the overall indirect effects of COVID-19 on maternal and child undernutrition and child mortality and explore possible mitigation strategies we used a ve-step process across three assumption scenarios (pessimistic, moderate, optimistic) ( Table 1).
In the rst step, we estimated changes in gross national income (GNI) per capita and poverty (% population<$1.90 per day) due to COVID-19 disruptions across 2020, 2021 and 2022 in 118 LMICs, using three different economic recovery scenarios. Second, we translated these different projections for GNI per capita into country-speci c changes in the prevalence of different levels of child wasting and maternal low BMI status using a recent statistical analysis that linked growth shocks to wasting and low BMI risks. Third, we inputted the estimates of poverty and wasting, along with assumptions about levels of disruption of health and nutrition services, into the Lives Saved Tool (LiST) to estimate changes in under-ve mortality, stunting and maternal anemia. Finally, we used the Optima-Nutrition model to explore possible strategies to mitigate the predicted increases in undernutrition and child mortality. The methods and inputs for each of these steps are detailed below.
For the rst step we used MIRAGRODEP, a global computable general equilibrium model linked to country-speci c household survey data, to predict the effects of COVID-19 disruptions on GNI per capita, household incomes and $1.90/day poverty rates between 2020-2022. 38 MIRAGRODEP inputs include international trade and nancial disruptions, as well as projected country estimates of COVID-19 cases and associated prevention measures (e.g. lockdowns). The economic channels of disruption included changes in labor force participation and labor productivity due to lockdown policies, increased morbidity and mortality, reduced e ciency of domestic and international transportation of goods, reduced consumer demand for in-person services (e.g. restaurants), and international shocks to trade and nancial ows (e.g. reduced demand for oil). For 2020, we modelled a single GNI scenario, as there is less uncertainty on the extent of economic disruption. (MIRAGRODEP results for 2020 were compared to the most recent economic forecasts from a range of international agencies.) However, we opted to model three different scenarios for economic recovery from the pandemic in 2021 and 2022. The optimistic scenario assumed a fast V-shaped economic recovery with economic activity accelerating quickly from 2021 onwards. The moderate scenario assumed a second infection wave into 2021 results in a "stop-start" W-shaped recovery. The pessimistic scenarios assumed a protracted U-shaped recovery with continued economic disruptions in 2021 and most countries not returning to pre-COVID-19 per capita income levels by 2022 (Table 1). For this analysis, the magnitude of macroeconomic disruption for the three scenarios is measured as the percentage difference between GNI per capita with and without COVID-19, while impacts on poverty -which are also used as a proxy for food insecurity (see below) -are measured as the difference in $1.90/day poverty rates with and without COVID-19.
Second, we used elasticities from a recent study 39 that linked economic growth (GNI) shocks to child wasting and maternal low BMI risks to generate predicted changes in wasting and low BMI prevalence. Speci cally, that study linked 177 Demographic Health Surveys from 52 LMICs to national level GNI growth shocks, and uncovered statistically signi cant negative relationships between changes in GNI per capita and: 1) changes in the prevalence of any (<-1SD WHZ), moderate/severe (<-2SD WHZ), and severe (<-3SD WHZ) wasting among children 0-59 months old and 2) prevalence of low Body Mass Index (BMI, <18.5 kg/m2) among mothers 15-49 years old. The corresponding elasticities from that study were then applied to country-speci c GNI growth projections from MIRAGRODEP, population projections and baseline undernutrition estimates from LiST to estimate increases in the number of children with wasting and number of women with low BMI as a result of the COVID-19 crisis.
LiST includes country-speci c population projections and other baseline assumptions from publicly available data sources. 40 This analysis included 118 LMIC with su cient coverage data (Web Annex 4); together these countries include over 95% of both global under-ve deaths and stunted children. Mean annual coverage reduction assumptions for ve preventive interventions across the three scenarios are consistent with the analyses by Roberton et al 18 and in line with disruptions reported elsewhere in 2020. (Table 1) We also included treatment of severe acute malnutrition (SAM) with similar coverage reduction assumptions but did not assume changes in coverage of treatment of moderate acute malnutrition (MAM), except in the optimistic scenario for 2022. For household food insecurity assumptions, which in uence the type of complementary feeding intervention applied (public provision of complementary foods in food insecure households versus only nutrition counseling in food secure households), we used the annualized MIRAGRODEP < $1.90/day poverty projections.
As detailed in Table 1 we assumed that service disruptions would continue after initial lockdowns but would become less severe over time and in all three scenarios would recover to half of the 2020 drop in 2021. Possible sources of ongoing disruptions include 1) health workers becoming infected and/or are diverted to care with new virus waves, 2) reduced use of available services by the population due to perceived risk of exposure and 3) reduced nancing over time due to economic impacts. For 2022, coverage levels in the pessimistic scenario remained lower than pre-COVID-19 baselines, while they returned to 2019 levels in the moderate scenario. For the optimistic scenario in 2022: (1) coverage for the majority of interventions was increased by 5% relative to 2019; (2) for treatment of MAM in children 6-59 months coverage increased to 10%; (3) multiple micronutrient supplements (MMS) replaced IFA during pregnancy; and (4) balanced protein-energy supplementation for pregnant women with low BMI was added at 10% coverage. We estimated the impacts of these last three interventions added in 2022 on adverse birth outcomes and under 5 child deaths.

Effects on long-term productivity
We used the Human Capital Approach to estimate lost productivity from the nutrition-related impacts of the COVID-19 pandemic. This approach calculates the present value of future productivity based on potential wages and potential time in the workforce. 41 This approach is similar to that adopted for estimating the bene ts of scaling up nutrition interventions in Shekar et al. 42 For this study, we used GNI per capita as a measure of average future wages. Estimates of lost productivity were calculated separately for outcomes of stunting, nutrition-related child mortality, and maternal anemia. Total excess cases of each outcome were based on the results of the LiST modelling previously described.
For each child death, years of potential productivity were calculated as the difference between age 18 and the country-speci c life expectancy or age 65, whichever is lower. The total number of children with potential lost productivity due to premature mortality was adjusted by the probability of death between age 5 and 18. Each year of productivity was valued using GNI per capita (current US$) adjusted for annual GNI growth, percent lifetime earnings that can be realized 43 and labor share of income. Future lost productivity was discounted at 3% per year. 44,45 For total lost productivity in each country, the lost productivity from each death is summed across all years of lost productivity and multiplied by the adjusted number of deaths.
The estimates of lost productivity for additional stunting cases used a similar approach as that described for child deaths. However, since stunting is expected to reduce future productive capacity for each child and not prevent future labor force participation, only this reduced productive capacity would be considered as potential lost productivity. Previous research estimated that decreased cognitive development due to early childhood malnutrition marked by stunting could lead to 21 percent reduction in adult earnings. 46 Therefore, the approach described for estimating lost productivity due to premature deaths were applied to the additional number of stunting cases and multiplied by 21 percent to derive an estimate for the productivity lost attributable to these additional stunting cases.
Excess cases of anemia in pregnant women were translated into lost earnings due to decreased labor productivity based on the methods described in Horton and Ross (2003) 46 . The level of productivity lost due to anemia differs depending on whether employment is in heavy manual labor, light manual labor, or service industry, with attributed productivity reductions of 17%, 5%, and 4% respectively. For each country, the distribution of types of labor engaged in by women was derived from the World Development Indicators (WDI) database. The proportion of women employed in agriculture, industry, and services were categorized as heavy manual labor, light manual labor, and service labor, respectively. Lost productivity was calculated separately for each category of employment as a product of per capita GNI, number of additional cases of maternal anemia in each year, percent of female employment in the speci c category, and the associated reduction in productivity in that category due to anemia. These estimates were adjusted for female labor force participation and labor share of income. Total lost productivity for each country was the sum of estimated productivity lost across the three employment categories and the three years (2020-2022) modelled, discounted at 3% per year.
Effects on the nancing landscape for nutrition To project how available donor and domestic resources for nutrition are expected to change across the three disruption scenarios, we developed a modelling approach based on Stuckler et al 47 . First, using Creditor Reporting System (CRS) data on o cial development assistance (ODA) from 2002-2018 48 , we ran a panel regression to estimate the elasticity of aid to nutrition-speci c and nutrition-sensitive sectors with respect to donor countries' economic growth. Then, we multiplied that elasticity by the MIRAGRODEP GNI growth projections to estimate the expected levels of aid to those sectors between 2020 and 2030. We conducted an analogous procedure to project the effect of domestic economic growth on domestic government health spending, using National Health Accounts panel data from WHO's Global Health Observatory 49 for the 118 countries used in the Optima Nutrition model.

Estimating additional intervention costs and optimized nutrition budget allocations
The Investment Framework for Nutrition estimated that approximately $7 billion per annum was needed to reach the WHA targets for stunting, wasting, maternal anemia, and breastfeeding by 2025. 42 Given the disruptions caused by the COVID-19 pandemic, we anticipate that more resources will be needed to address the increased burden of malnutrition. We estimated the additional resource needs to address the expected increased in stunting, wasting, and maternal anemia as the product of additional burden of each outcome estimated from the LiST modelling and the cost per case of stunting or anemia averted or case of severe wasting treated.
We used the Optima Nutrition model 50 to illustrate how 2021-2022 nancing could be optimally allocated across six nutrition interventions to maximize the number of "alive and non-stunted" children. Optima Nutrition is a cohort model that tracks children until ve years of age, categorised according to their mother's breastfeeding practices, family economic status, height-for-age (stunting) status and weight-for-height (wasting) status. Children in the model can die from a range of age-speci c causes, with the relative risks of dying from each cause related to the child's breastfeeding, stunting and wasting status. Interventions can improve nutritional outcomes directly or indirectly by reducing risk factors including birth outcomes and diarrhoea incidence. The model includes an optimisation algorithm, which can be used to incrementally shift a xed amount of funding between interventions until it achieves a budget allocation that maximizes (or minimizes) a given objective. For this analysis the objective of maximizing alive and non-stunted children was selected to identify a priority mix of interventions to both reduce mortality from severe wasting and reduce stunting.
For each of the 118 LMICs, the total expenditure on the six nutrition interventions in 2019 and 2020 was estimated by multiplying coverage estimates from LiST from the moderate scenario (Table 1) by country-speci c unit costs (Web Annex). Given evidence for a lagged decline in ODA starting in 2022 (Web Annex), we assumed total available nancing for the nutrition interventions in 2021 and 2022 would equal total 2019 expenditure. The model was projected for 2020-2022 inclusive. The pre-optimization epidemiological projections and intervention coverages were aligned with the moderate scenario (Table 1) and were compared to outcomes when the funding was optimized to determine the maximum number of stunting cases and child deaths that could be averted through allocative e ciency.

Declarations
The Standing Together for Nutrition Consortium: The Standing Together for Nutrition (STfN) consortium is a multidisciplinary consortium of nutrition, economics, food and health system experts, currently consisting of 51 individuals from 32 organisations in HIC and LMIC, working to address the scale and reach of COVID-related nutrition challenges (See Web Annex 3).
The authors contributions were as follows: Writing and modelling group responsible for conceptualization, design of the study, primary analyses and the main paper writing and editing JKA, REB, DH, RH, SO, MR, NS, MS, NW.
Contributors involved in conceptualization, analyses of sub-section, writing of panels or sub-sections: AF, LH, DL, AS, MT.
Contributors involved in conceptualization and review of nal paper: see web annex.
All authors were involved in the conceptualization and reviewed and approved the nal version of the manuscript. SO, DH, MR, LH and AF have received nancial support from the Children's Investment Fund Foundation in support for this research. The funders had no role in the analysis and interpretation of the evidence or in writing the paper and the decision to submit for publication. The other authors declare that they have no con icts of interest. As corresponding author Saskia Osendarp states that she has full access to all data and nal responsibility for the decision to submit for publication.  Optimization of interventions to reduce child stunting and child mortality. Notes: Left bar: estimated expenditure on selected nutrition interventions in 2019, calculated by combining coverage estimates (medium scenario) and unit cost estimates. Right bar: optimized budget allocation to maximize alive and non-stunted children, with total funding envelope estimated from ODA projections relative to 2019. Results are aggregated over 118 countries, and variations exist across countries due to demographic, epidemiological and economic factors. Breastfeeding promotion includes both early initiation and exclusive breastfeeding promotion

Supplementary Files
This is a list of supplementary les associated with this preprint. Click to download. WebAnnex1Table1FINAL.docx WebAnnex2.docx WebAnnex3STfNauthors.docx WebAnnex4listofcountries07122020.pdf