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The COVID-19 outbreak had severe adverse impacts on the health and wealth of households in lower-income countries (LICs), and has affected even more severely female-headed households in LICs. Using high-frequency phone surveys in Sierra Leone, we show that female-headed households are likely to rely on cheaper food alternatives (e.g., Cassava) compared to maleheaded households and are more food insecure. These effects are more nuanced among the poorest families owning one or no assets. Furthermore, female-headed households had less access to COVID-19 information, were less likely to adopt preventive measures (e.g., masks and social distancing) at the onset of the pandemic, and show greater signs of vaccine hesitancy in the early stages of the COVID-19 vaccine campaign.

Two years after COVID-19 vaccine rollouts began, COVID-19 vaccination rates in low- and middle-income countries (LMICs) continue to lag. Tracing individual country experiences with vaccine procurement in the early stages of the pandemic suggests that international supply chain failures caused initial delays. High vaccine hesitancy in the population and last-mile delivery challenges within LMICs were other possible limiting factors. This paper summarizes descriptive and experimental research on vaccine demand and supply in LMICs to evaluate these competing claims. The weight of the evidence suggests that external supply restrictions and internal distribution challenges (rather than vaccine hesitancy) appear to be paramount.

This paper studies the welfare effects of encouraging rural–urban migration in the developing world. To do so, we build and analyze a dynamic general‐equilibrium model of migration that features a rich set of migration motives. We estimate the model to replicate the results of a field experiment that subsidized seasonal migration in rural Bangladesh, leading to significant increases in migration and consumption. We show that the welfare gains from migration subsidies come from providing better insurance for vulnerable rural households rather than from correcting spatial misallocation by relaxing credit constraints for those with high productivity in urban areas that are stuck in rural areas.

In the first six months of COVID-19 vaccine distribution, over 90% of all doses were given to residents of high and upper middle income nations. Less than 30% of Africans were vaccinated with at least one shot even 18 months after vaccine development. This has led to an explosion of scholarly and policy interest on vaccine hesitancy and ways to overcome it. We argue instead that the limiting factor for many rural Africans is lack of access, and implemented an intervention designed to overcome the logistical challenges of last-mile delivery. The cluster randomized controlled trial in 150 remote rural communities shows that simply bringing vaccines to villages using mobile vaccination teams increases the community vaccination rate by 20 percentage points within just 48-72 hours. Moreover, auxiliary populations showed up at our temporary clinic to get vaccinated, which lowers the cost of this intervention to US$ 32 per person vaccinated. This is more cost-effective than most vaccination strategies investigated via trials.

We track the effects of the COVID-19 pandemic on mental health in eight Low and Middle Income Countries (LMICs) in Asia, Africa, and South America utilizing repeated surveys of 21,162 individuals. Many respondents were interviewed over multiple rounds pre- and post-pandemic, allowing us to control for time trends and within-year seasonal variation in mental health. We demonstrate how mental health fluctuates with agricultural crop cycles, deteriorating during pre-harvest “lean” periods. Ignoring this seasonal variation leads to unreliable inferences about the effects of the pandemic. Controlling for seasonality, we document a large, significant, negative impact of the pandemic on mental health, especially during the early months of lockdown. In a random effects aggregation across samples, depression symptoms increased by around 0.3 standard deviations in the four months following the onset of the pandemic. The pandemic could leave a lasting legacy of depression. Absent policy interventions, this could have adverse long-term consequences, particularly in settings with limited mental health support services, which is characteristic of many LMICs.

Widespread acceptance of COVID-19 vaccines is crucial for achieving sufficient immunization coverage to end the global pandemic, yet few studies have investigated COVID-19 vaccination attitudes in lower-income countries, where large-scale vaccination is just beginning. We analyze COVID-19 vaccine acceptance across 15 survey samples covering 10 low- and middle-income countries (LMICs) in Asia, Africa and South America, Russia (an upper-middle-income country) and the United States, including a total of 44,260 individuals. We find considerably higher willingness to take a COVID-19 vaccine in our LMIC samples (mean 80.3%; median 78%; range 30.1 percentage points) compared with the United States (mean 64.6%) and Russia (mean 30.4%). Vaccine acceptance in LMICs is primarily explained by an interest in personal protection against COVID-19, while concern about side effects is the most common reason for hesitancy. Health workers are the most trusted sources of guidance about COVID-19 vaccines. Evidence from this sample of LMICs suggests that prioritizing vaccine distribution to the Global South should yield high returns in advancing global immunization coverage. Vaccination campaigns should focus on translating the high levels of stated acceptance into actual uptake. Messages highlighting vaccine efficacy and safety, delivered by healthcare workers, could be effective for addressing any remaining hesitancy in the analyzed LMICs., Survey data collected across ten low-income and middle-income countries (LMICs) in Asia, Africa and South America compared with surveys from Russia and the United States reveal heterogeneity in vaccine confidence in LMICs, with healthcare providers being trusted sources of information, as well as greater levels of vaccine acceptance in these countries than in Russia and the United States.

Persuading people to mask Even in places where it is obligatory, people tend to optimistically overstate their compliance for mask wearing. How then can we persuade more of the population at large to act for the greater good? Abaluck et al . undertook a large, cluster-randomized trial in Bangladesh involving hundreds of thousands of people (although mostly men) over a 2-month period. Colored masks of various construction were handed out free of charge, accompanied by a range of mask-wearing promotional activities inspired by marketing research. Using a grassroots network of volunteers to help conduct the study and gather data, the authors discovered that mask wearing averaged 13.3% in villages where no interventions took place but increased to 42.3% in villages where in-person interventions were introduced. Villages where in-person reinforcement of mask wearing occurred also showed a reduction in reporting COVID-like illness, particularly in high-risk individuals. —CA

The COVID-19 pandemic has upended health and living standards around the world. This article provides an interim overview of these effects, with a particular focus on low- and middle-income countries (LMICs). Economists have explained how the pandemic is likely to have different consequences for LMICs and demands distinct policy responses compared to those of rich countries. We survey the rapidly expanding body of empirical research that documents the pandemic's many adverse economic and noneconomic effects in terms of living standards, education, health, and gender equality, which appear to be unprecedented in scope and scale. We also review research on successful and failed policy responses, including the failure to ensure widespread vaccine coverage in many LMICs, which is needed to end the pandemic. We close with a discussion of implications for public policy in LMICs and for the institutions of international governance, given the likelihood of future pandemics and other major shocks (e.g., climate).

The COVID-19 pandemic has upended health and living standards around the world. This article provides an interim overview of these effects, with a particular focus on low- and middle-income countries (LMICs). Economists have explained how the pandemic is likely to have differential consequences for LMICs, and demand distinct policy responses, compared to rich countries. We survey the rapidly expanding body of empirical research that documents its many adverse economic and non-economic effects in terms of living standards, education, health, and gender equality, which appear to be unprecedented in depth and scale. We also review research on successful and failed policy responses, including the failure to ensure widespread vaccine coverage in LMICs, which is needed to end the pandemic. We close with a discussion of implications for public policy in LMICs, and for the institutions of international governance, given the likelihood of future pandemics and other major shocks (e.g., climate).

Addressing public health externalities often requires community-level collective action. Each person’s sanitation behavior can affect the health of neighbors. We report on a cluster randomized controlled trial conducted with 19,000 households in rural Bangladesh where we randomized (1) either group financial incentives or a non-financial “social recognition” reward, and (2) asking each household to make either a private pledge or a public pledge to maintain hygienic latrines. The group financial reward has the strongest impact in the short term (3 months), inducing a 7.5-12.5 percentage point increase in hygienic latrine ownership. Getting people to publicly commit to maintaining and using a hygienic latrine in front of their neighbors induced a 4.2-6.1 percentage point increase in hygienic latrine ownership in the short term. In the medium term (15 months), the effect of the financial reward dissipates while the effect of the public commitment persists. Neither social recognition nor private commitments produce effects statistically distinguishable from zero.

A randomized-trial of community-level mask promotion in rural Bangladesh during COVID-19 shows that the intervention tripled mask usage and is a cost-effective means of promoting public health.

We analyze COVID-19 vaccine acceptance across 15 survey samples covering ten low- and middle-income countries (LMICs) in Asia, Africa, and South America, Russia (an upper-middle-income country), and the United States, using survey responses from 44,260 individuals. We find considerably higher willingness to take a COVID-19 vaccine in LMIC samples (80% on average) compared to the United States (65%) and Russia (30%). Vaccine acceptance was primarily explained by an interest in personal protection against COVID-19, while concern about side effects was the most commonly expressed reason for reluctance. Health workers were the most trusted sources of information about COVID-19 vaccines. Our findings suggest that prioritizing vaccine distribution to LMICs should yield high returns in promoting global immunization coverage, and that vaccination campaigns in these countries should focus on translating acceptance into uptake. Messaging highlighting vaccine efficacy and safety, delivered by healthcare workers, may be most effective in addressing remaining hesitancy.

Attempts to curb undesired behavior through regulation gets complicated when agents can adapt to circumvent enforcement. We test a model of enforcement with learning and adaptation, by auditing vendors selling illegal fish in Chile in a randomized controlled trial, and tracking them daily using mystery shoppers. Conducting audits on a predictable schedule and (counter-intuitively) at high frequency is less effective, as agents learn to take advantage of loopholes. A consumer information campaign proves to be almost as cost-effective and curbing illegal sales, and obviates the need for complex monitoring and policing. The Chilean government subsequently chooses to scale up this campaign. Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Migration and pollution are two defining features of China's impressive growth performance over the last 30 years. In this paper we study the migration response to pollution in Chinese cities, and its consequences for productivity and welfare. We document a robust pattern in which skilled workers emigrate more in response to pollution than the unskilled. Their greater sensitivity to air quality holds up in cross-sectional variation across cities, panel variation with individual fixed-effects, and when instrumenting for pollution using distant power-plants upwind of cities, or thermal inversions that trap pollution. Pollution therefore changes the spatial distribution of skilled and unskilled workers, which results in higher returns to skill in cities that the educated migrate away from. We quantify the loss in aggregate productivity due to this re-sorting by estimating a model of demand and supply of skilled and unskilled workers across Chinese cities. Counterfactual simulations from the estimated model show that reducing pollution would increase productivity through spatial re-sorting by approximately as much as the direct health benefits of clean air. Physical and institutional restrictions on mobility exacerbate welfare losses. People's dislike of pollution explains a substantial portion of the wage gap between cities.

Recent studies find that observational returns to rural-urban migration are near zero in three developing countries. We revisit this result using panel tracking surveys from six countries, finding higher returns on average. We then interpret these returns in a multi-region Roy model with heterogeneity in migration costs. In the model, the observational return to migration confounds the urban premium and the individual benefits of migrants, and is not directly informative about the welfare gain from lowering migration costs. Patterns of regional heterogeneity in returns, and a comparison of experimental to observational returns, are consistent with the model’s predictions.

Using detailed microdata, we document how migration-dependent households are especially vulnerable during the COVID-19 pandemic. We create pre- and post-COVID panel datasets for three populations in Bangladesh and Nepal, leveraging experimental and observational variation in prior migration dependence. We report 25 per cent greater declines in earnings and fourfold greater prevalence of food insecurity among migrant households since March. Causes include lower migration rates, less remittance income per migrant, isolation in origin communities, and greater health risks. We compile a large set of secondary data to demonstrate the extent of vulnerability worldwide and conclude with recommendations for policy targeted at migrants.

We use a two-stage experiment to study how a short-term subsidy for a new product affects uptake, usage, and future demand for the same product (a new solar lamp). We use an auction design to gauge willingness-to-pay, and randomly vary the strike price across villages to create random variation in purchase prices and uptake across villages. Our main results are that subsidies do not adversely affect subsequent product use, but stimulate uptake. If subsidies depress future willingness-to-pay, then this effect is outweighed by additional learning about the benefits of the new product. The net effect is that short-term subsidies increase future willingness-to-pay. However; prices play an important allocative role, and lowering prices via subsidies encourages uptake by households with low use intensity. We do not find any evidence supporting social learning and anchoring beyond the initial sample of beneficiaries.

Decentralization can improve service delivery, but it can also generate externalities across jurisdictional boundaries. We examine the nature and size of water pollution externalities as rivers flow across jurisdictions. Panel data on water pollution in Brazilian rivers coupled with county splits that change the locations of borders allow us to identify the spatial patterns of pollution as rivers approach and cross borders, controlling for fixed effects and trends specific to each location. The theory of externalities predicts that pollution should increase at an increasing rate as the river approaches the downstream exit border, that there should be a structural break in the slope of the pollution function at the border, and that a larger number of managing jurisdictions should exacerbate pollution externalities. We find support for all four predictions in the data. Satellite data on growth in night-time lights along rivers show that local authorities allow more settlements to develop close to rivers in the downstream portions of counties, which is the likely underlying mechanism. The border effects on pollution are not as pronounced when the cost of inter-jurisdictional coordination is lower.

We document that an experimental intervention offering transport subsidies for poor rural households to migrate seasonally in Bangladesh improved risk sharing. A theoretical model of endogenous migration and risk sharing shows that the effect of subsidizing migration depends on the underlying economic environment. If migration is risky, a temporary subsidy can induce an improvement in risk sharing and enable profitable migration. We estimate the model and find that the migration experiment increased welfare by 12.9%. Counterfactual analysis suggests that a permanent, rather than temporary, decline in migration costs in the same environment would result in a reduction in risk sharing.

Do new migration opportunities for rural households change the nature and extent of informal risk sharing? We experimentally document that randomly offering poor rural households subsidies to migrate leads to a 40% improvement in risk sharing in their villages. We explain this finding using a model of endogenous migration and risk sharing. When migration is risky, the network can facilitate migration by insuring that risk, which in turn crowds-in risk sharing when new migration opportunities arise. We estimate the model and find that welfare gains from migration subsidies are 42% larger, compared with the welfare gains without spillovers, once we account for the changes in risk sharing. Our analysis illustrates that (a) ignoring the spillover effects on the network gives an incomplete picture of the welfare effects of migration, and (b) informal risk sharing may be an essential determinant of the takeup of new income-generating technologies.

We explain stable growth performance in democracies by characterizing political systems in terms of the distribution of political power across groups, and show when the qualities of policy alternatives are uncertain, greater democracy (decentralization of authority) leads to more stable policy choices. We empirically test this mechanism by creating measures of the inter-temporal variability in fiscal and trade policies. In an array of specifications (cross-sectional, panel with fixed-effects, matching models, instrumental variables, difference-in-difference), we show that policy choices are significantly more stable over time in democracies. This mechanism explains a large part of the negative link between democracy and output volatility.

With minimal statistical or theoretical assumptions, randomized controlled trials (RCTs) provide a necessary input for poverty analysis: credibly estimated causal relationships. But complexities arise when moving from RCT research results to anti-poverty policy, with unintended consequences. RCT evidence by itself offers an incomplete prediction of the effects of policy, due to heterogenous effects, spillovers and general equilibrium changes, macroeconomic and welfare effects, political economy reactions, and implementation challenges, when programs are scaled. We suggest strategies for tightening the link between development research and anti-poverty policy, for example, by changing the practice of RCTs to be more ambitious about what is randomized, and to combine the analysis of experimental data with other rigorous methods that go beyond estimating treatment effects. We describe our efforts to encourage and coordinate this type of work via a new research initiative.

Even with comparable innate ability and performance, women may be subject to discrimination. We run a field experiment across 143 Malawian villages in which either men or women were assigned the task of learning about a new agricultural technology, and then communicating it to others to convince them to adopt. Objective measures of these communicators’ knowledge and adoption of the new technology show no gender gap in their ability to acquire, retain and use the information. Yet, micro-data on individual interactions from 6500 farmers show that other farmers are less willing to learn from female communicators, whom they perceive not to be as good at farming as their male counterparts. In spite of this, other farmers learn just as much about the technology when the communicator role is reserved for women, and they experience similar farm yields.

Attempts to curb illegal activity by enforcing regulations gets complicated when agents react to the new regulatory regime in unanticipated ways to circumvent enforcement. We present a research strategy that uncovers such reactions, and permits program evaluation net of such adaptive behaviors. Our interventions were designed to reduce over-fishing of the critically endangered Pacific hake by either (a) monitoring and penalizing vendors that sell illegal fish or (b) discouraging consumers from purchasing using an information campaign. Vendors attempt to circumvent the ban through hidden sales and other means, which we track using mystery shoppers. Instituting random monitoring visits are much more effective in reducing true hake availability by limiting such cheating, compared to visits that occur on a predictable schedule. Monitoring at higher frequency (designed to limit temporal displacement of illegal sales) backfires, because targeted agents learn faster, and cheat more effectively. Sophisticated policy design is therefore crucial for determining the sustained, longer-term effects of enforcement. Data collected from fishermen, vendors, and consumers allow us to document the upstream, downstream, spillover, and equilibrium effects of enforcement on the entire supply chain. The consumer information campaign generates two-thirds of the gains compared to random monitoring, but is simpler for the government to implement and almost as cost-effective., 63 pages; Keywords: Enforcement, Regulation, Law and Economics, Fisheries; JEL Classification Codes: K42, O1, L51

In order to induce farmers to adopt a productive new agricultural technology, we apply simple and complex contagion diffusion models on rich social network data from 200 villages in Malawi to identify seed farmers to target and train on the new technology. A randomized controlled trial compares these theory-driven network targeting approaches to simpler strategies that either rely on a government extension worker or an easily measurable proxy for the social network (geographic distance between households) to identify seed farmers. Our results indicate that technology diffusion is characterized by a complex contagion learning environment in which most farmers need to learn from multiple people before they adopt themselves. Network theory based targeting can out-perform traditional approaches to extension, and we identify methods to realize these gains at low cost to policymakers. Keywords: Social Learning, Agricultural Technology Adoption, Complex Contagion, Malawi JEL Classification Codes: O16, O13, 61 pages

In order to induce farmers to adopt a productive new agricultural technology, we apply simple and complex contagion diffusion models on rich social network data from 200 villages in Malawi to identify seed farmers to target and train on the new technology. A randomized controlled trial compares these theory-driven network targeting approaches to simpler strategies that either rely on a government extension worker or an easily measurable proxy for the social network (geographic distance between households) to identify seed farmers. Our results indicate that technology diffusion is characterized by a complex contagion learning environment in which most farmers need to learn from multiple people before they adopt themselves. Network theory based targeting can out-perform traditional approaches to extension, and we identify methods to realize these gains at low cost to policymakers.

This paper studies the welfare effects of encouraging rural-urban migration in the developing world. To do so, we build a dynamic incomplete-markets model of migration in which heterogeneous agents face seasonal income fluctuations, stochastic income shocks, and disutility of migration that depends on past migration experience. We calibrate the model to replicate a field experiment that subsidized migration in rural Bangladesh, leading to significant increases in both migration rates and consumption for induced migrants. The model’s welfare predictions for migration subsidies are driven by two main features of the model and data: first, induced migrants tend to be negatively selected on income and assets; second, the model’s non-monetary disutility of migration is substantial, which we validate using newly collected survey data from this same experimental sample. The average welfare gains are similar in magnitude to those obtained from an unconditional cash transfer, and greater than from policies that discourage migration, though migration subsidies lead to larger gains for the poorest households, which have the greatest propensity to migrate.

Helping the poor invest in sanitation Almost a third of the world's people do not have access to hygienic latrines. Improving access to and increasing the use of latrines would reduce deaths and poor health caused by diarrheal disease. Guiteras et al. tested the relative benefits of supplying health information, offering a financial subsidy to purchasers of hygienic latrines, or increasing the availability of latrines for purchase. Providing the subsidy worked best: Nonsubsidized households were more likely to purchase latrines when other households in their village were subsidized. Science , this issue p. 903

Rural to urban migration is an integral part of the development process, but there is little evidence on how out-migration transforms rural labor markets. Emigration could benefit landless village residents by reducing labor competition, or conversely, reduce productivity if skilled workers leave. We offer to subsidize transport costs for 5792 potential seasonal migrants in Bangladesh, randomly varying saturation of offers across 133 villages. The transport subsidies increase beneficiaries’ income due to better employment opportunities in the city, and also generate the following spillovers: (a) A higher density of offers increases the individual take-up rate, and induces those connected to offered recipients to also migrate. The village emigration rate increases from 35% to 65%. (b) This increases the male agricultural wage rate in the village by 4.5-6.6%, and the available work hours in the village by 11-14%, which combine to increase income earned in the village, (c) There is no intra-household substitution in labor supply, but primary workers within households earn more during weeks in which many of their village co-residents moved away. (d) The wage bill for agricultural employers increases, which reduces their profit, with no significant change in yield. (e) Food prices increase by 2.7% on net, driven by an increase in the price of (fish) protein, and offset by (f) a decrease in the price of non-tradables like prepared food and tea. Seasonal migration subsidies not only generate large direct benefits, but also indirect spillover benefits by creating slack in the village-of-origin labor market during the lean season.

This paper uses a wealth shock from the construction of a flood protection embankment in rural Bangladesh coupled with data on the universe of all 52,000 marriage decisions between 1982 and 1996 to examine changes in marital prospects for households protected by the embankment relative to unprotected households living on the other side of the river. We use difference-in-difference specifications to document that brides from protected households commanded larger dowries, married wealthier households, and became less likely to marry biological relatives. Financial liquidity-constrained households appear to use within-family marriage (in which one can promise ex-post payments) as a form of credit to meet up-front dowry demands, but the resultant wealth shock for households protected by the embankment relaxed this need to marry consanguineously. Our results shed light on the socioeconomic roots of consanguinity, which carries health risks for offspring but can also carry substantial benefits for the families involved.