Observational data collected prior to the pandemic (between 2004 and 2019) were used to simulate the potential consequences of early childhood care and education (ECCE) service closures on the estimated 167 million preprimary-age children in 196 countries who lost ECCE access between March 2020 and February 2021. COVID-19-related ECCE disruptions were estimated to result in 19.01 billion person-days of ECCE instruction lost, 10.75 million additional children falling “off track” in their early development, 14.18 million grades of learning lost by adolescence, and a present discounted value of USD 308.02 billion of earnings lost in adulthood. Further burdens associated with ongoing closures were also forecasted. Projected developmental and learning losses were concentrated in low- and lower middle-income countries, likely exacerbating long-standing global inequities.
We used a variety of pre‐pandemic data sources to complete our analyses. For all of our analyses, we used the most recently available data on school closures (covering March 11, 2020 to February 2, 2021) from UNICEF and UNESCO. We also used the World Bank’s 2020 classifications to categorize countries into high‐, upper middle‐, lower middle‐, and low‐income groupings (World Bank, 2020). In addition to these sources, to estimate the number of person‐days of ECCE instruction lost (Outcome 1), we used data on ECCE participation rates from UNESCO’s Institute for Statistics (UIS), the UNICEF‐supported Multiple Indicator Cluster Surveys (MICS), and other data sources, along with the number of ECCE‐age children from UNESCO and the World Population Prospects. Second, to estimate the number of children who became off track in their early childhood development (Outcome 2), we used data on ECCE and early childhood development from the MICS. Third, to estimate the number of grades of academic learning lost by adolescence (Outcome 3), we used data on ECCE and adolescent learning from the Programme for International Student Assessment (PISA). Each of these data sources is described in detail below. Finally, to estimate the total earnings lost into adulthood (Outcome 4), we extracted rates of returns (% increase in wages) to schooling from a prior review by Fink and colleagues (2016) and used random‐effects meta‐analysis to compute average returns to schooling for country income groups. Our full sample comprises all countries with national data on ECCE participation (N = 196 countries, representing 99% of the global under‐five population). Our primary source of ECCE participation data was UNESCO’s UIS ECCE database (http://data.uis.unesco.org/; n = 143 countries), which provides information on net ECCE enrollment, defined as the total number of preschool‐age children enrolled in preschool education, and expressed as a percentage of the total population in that age. We prioritized data from UNESCO given that it is the source of information for tracking ECCE participation in the SDGs, and it is also available for the largest number of countries. Where UNESCO data were not available, we extracted ECCE data from MICS surveys (https://mics.unicef.org/, n = 30), which report data on ECCE attendance, defined as the percentage of children 36–59 months currently attending an early childhood educational program. Where neither source was available, we used an online search of official and recognized sources such as Ministries of Education, national censuses, and national household surveys to find the latest participation rates for individual countries (n = 23 countries). Table S1 in the Supporting Information details the final list of countries included in our analysis and the source and definition of ECCE participation data for each. Although UNESCO and the MICS use different definitions of ECCE participation, both sources consider a wide and inclusive set of program types, including public, private, and non‐profit programs, as well as full‐ and part‐time programs. Appendix A in the Supporting Information provides further details regarding analyses examining differences in country‐level ECCE participation rates reported by UNESCO versus MICS for countries in which both data sources were available. In sum, these analyses suggested no evidence for systematic differences across these datasets. Table Table11 Column 4 shows overall rates of ECCE participation by country income group prior to the COVID‐19 pandemic. Rates of participation ranged from a low of approximately 20% in low‐income countries to nearly 80% in high‐income countries. Pre‐COVID‐19 ECCE‐age population, ECCE participation rates, number of children in ECCE, and percent instruction days lost to COVID‐19 This table aggregates populations of children across countries, but presents averages for country‐level participation rates. Data on the total number of ECCE‐age children in each country were obtained from UNESCO (n = 193 countries) and the World Population Prospects (n = 3 countries). The UNESCO definition of ECCE‐age children targets children age 3 years until the starting age of primary education, which is 6 years in most countries (UNESCO, 2012). Accordingly, the ECCE target population typically comprises three annual birth cohorts in each country. Table S1 presents further details on the official starting age of primary education by country, and Table Table11 Column 3 shows the total number of ECCE‐aged children in millions by country income group. In total, 347 million children were estimated to be of ECCE age prior to COVID‐19, the majority of whom lived in lower (150 million) and upper (105 million) middle‐income countries. To estimate short‐term associations between ECCE and early childhood development, we used data from 174,018 3‐ and 4‐year‐old children in 61 countries participating in the MICS (M age = 47.33 months, range = 36–59 months; 49% girls; race/ethnicity not available). MICS include nationally representative data on child and family wellbeing, with a focus on low‐ and middle‐income countries (UNICEF, 2006). Standard MICS questionnaires include questions regarding whether 3‐ and 4‐year‐old children currently attend ECCE programs (yes/no). The early development of these same children is also measured using the Early Childhood Development Index (ECDI). The ECDI includes 10 caregiver‐reported items capturing 3‐ and 4‐year‐old children’s early literacy/numeracy (three items), physical (two items), social‐emotional (three items), and approaches to learning (two items) skills (Loizillon et al., 2017). Following MICS recommendations, children were considered developmentally off track in the ECDI if they failed more than one item in two or more of these domains. Despite criticisms regarding the coarseness of this measure (McCoy et al., 2016), the ECDI is highly policy‐relevant given its current status as the indicator of early childhood development for SDG 4.2.1 (United Nations, 2019). Since the countries that participated in the MICS varied across years, we chose the most recently available dataset for each country. Table S1 lists the specific countries included in our MICS dataset. To estimate associations between ECCE and medium‐term learning outcomes, we used data for 426,125 adolescents in 76 countries participating in the PISA (M age = 15.79 years, range = 15.08–16.33 years; 52% girls; race/ethnicity not available). The PISA is an international survey program that includes direct assessments of reading, mathematics, and science literacy every 3 years for nationally representative samples of 15‐year‐old students enrolled in school, focusing on higher‐income countries (OECD, 2019). The PISA also includes a retrospective item in which respondents report how many years of school‐ or center‐based ECCE they attended, as defined by the International Standard Classification of Education Level 0 (ISCED‐0). Similar to the MICS data, we chose the most recently available PISA dataset for each country. Table S1 lists the specific countries included in our PISA dataset. For all of our analyses, we used the most recently available data on school closures caused by COVID‐19 from UNICEF and UNESCO (https://data.unicef.org/resources/one‐year‐of‐covid‐19‐and‐school‐closures/). Specifically, we estimated the number of instruction days lost in each country by adding the total number of days that schools were closed plus half the number of days that schools were partially closed between March 11, 2020 and February 2, 2021. We then calculated the proportion of instruction days lost due to COVID‐19 for each country by dividing this number by the total number of possible instructional days during this period (see Figure Figure1).1). As shown in Table Table11 Column 6, globally children lost an average of 52.67% of ECCE instructional days during the first 11 months of the pandemic, with the largest percentages of instructional days lost in middle‐income countries. Estimated percentage of days of ECCE instruction lost due to COVID‐19‐related ECCE closures between March, 2020 and February, 2021, by country. Note. See Table S3 for country‐level details Our primary analyses estimating the implications of COVID‐19‐related ECCE closures on each of our study’s four primary outcomes are described below. First, we estimated the total number of person‐days of ECCE instruction lost due to COVID‐19‐related school closures during the first 11 months of the pandemic (i.e., between March 2020 and February 2021). To do so, we began by multiplying the latest available estimates of the proportion of children participating in ECCE prior to COVID‐19 by the total number of ECCE‐age children in each country. The resulting total number of children participating in ECCE in each country prior to COVID‐19 was then multiplied by the number of instructional days lost between March 2020 and February 2021 in each country (Equation 1): We then summed each country’s total number of person‐days of ECCE instruction lost to COVID‐19 within country income groups. Second, we used MICS data to estimate the likely implications of ECCE closures during the first 11 months of the pandemic for early childhood development. To do so, we used a series of country‐specific logistic regression models in which a binary indicator for whether children were developmentally off track (OffTracki) was regressed on a binary indicator representing whether children were attending ECCE versus receiving alternative forms of care (most typically staying home with their parents or other caregivers; ECCEi). These equations also included a vector of control variables, including child i’s age in months, gender, household wealth, maternal educational attainment, an indicator for rural versus urban residence, and a sum index of caregivers’ engagement in six play and learning activities (i.e., reading, singing, telling stories, playing, taking the child outside for a walk, and counting) that has been shown to predict early childhood development (Jeong et al., 2017; Equation 2): We stored the estimated coefficients from these country‐level models and employed them to obtain predicted values for the outcome variable. Using these predicted values, we estimated the likely increase in the proportion of children off track in their development by scaling the estimates by the median duration of ECCE participation in each country income group reported in the PISA dataset. According to the PISA dataset, the average duration of pre‐COVID‐19 ECCE attendance was 1 year in low‐ and lower middle‐income countries, and 2 years in upper middle‐ and high‐income countries. This implies, for example, that a 180‐day closure of ECCE would result in a complete (100%) loss of the typical developmental benefits of ECCE for a child about to start ECCE in a low‐ or lower‐middle income country with 180 instructional days per year, and to a 50% loss of the protective benefits in upper middle‐ and high‐income countries with the same total instructional days per year. We then used random‐effects meta‐analysis to pool estimates of the likely increase in the proportion of children off track in their development by country income group from the country‐level predictions from Equation 2. Finally, we applied these country income group‐level estimates of the proportion of children who would fall developmentally off track as a result of ECCE closures to the total population of ECCE‐age children to obtain estimates of the number of children whose early development might be compromised by ECCE disruptions in the first 11 months of the pandemic. Third, we used PISA data to predict the estimated consequences of ECCE closures between March 2020 and February 2021 on adolescent learning losses. For this analysis, we created a single academic achievement score summarizing students’ performance in the reading, math, and science domains of PISA. This first principal component of the three scores captured 94% of total variance, suggesting a very high correlation across the domain‐specific assessments. To facilitate interpretation, we standardized the composite PISA achievement variable to a mean of 0 and to a standard deviation of 1. Similar to the analyses predicting early development, we used multivariate regression models to estimate country‐specific associations between the number of years adolescents reported participating in ECCE (YearsECCEi; where 0 indicates they received care outside of ECCE, e.g., at home) and their composite achievement scores (zPISAi) while controlling for students’ grade levels, ages, household wealth, and parental educational attainment (Equation 3): Given that most countries in the PISA dataset capped reporting of years of ECCE at three and, according to UNESCO statistics, in most countries preprimary education comprised 3 years (between ages three and six), records reporting more than 3 years of ECCE participation (i.e., 20% of the sample) were top‐coded at three. Furthermore, certain PISA datasets only reported the minimum number of years of ECCE (“at least one,” “at least two,” etc.); we used these minimums as proxies for actual ECCE exposure in these datasets (e.g., “at least one” was replaced with 1). Similar to the analyses for early childhood development described above, we first estimated country‐specific associations between ECCE participation and adolescent learning outcomes, and then used random‐effect meta‐analysis to derive pooled estimates of these associations for each country income group. Given that PISA data are unavailable for low‐income countries, we used the estimate derived for lower middle‐income countries for the low‐income group. In a set of sensitivity analyses, we also explored the extent to which results differed when assuming relative returns to ECCE in low‐income countries of 50% and 150% of those observed in lower middle‐income countries. To translate composite PISA scores into a more easily interpretable (and more labor market‐relevant) outcome measure, we converted additional PISA scores to school grade equivalents. To do so, we estimated the average increase in PISA scores associated with an additional grade completed in each country using the coefficient for Gradei in Equation 3. Using meta‐analysis, we then created a country income group‐specific estimate of average annual improvements in academic achievement for each additional grade completed (ΔzPISAgrade). This estimate then allowed us to convert observed academic achievement losses into (effective) grades of learning lost by adolescence taking into account the average days of instruction lost (Closures) as shown in Equation 4: Fourth, we converted the anticipated losses in adolescent learning due to COVID‐19‐related ECCE closures in the first 11 months of the pandemic into estimates of future reductions in labor market incomes. A large economics literature has highlighted the high labor market returns to additional grades of schooling attainment (e.g., Psacharopoulos & Patrinos, 2004, 2018). We extracted rates of returns (% increase in wages) to schooling from a prior review by Fink and colleagues (2016) and used random‐effects meta‐analysis to compute average returns to schooling for country income groups. Following Fink and colleagues (2016), we estimated the net present value of future wage losses per child and cohort assuming that children will work in the labor market from age 20 to 60, with 2% annual growth in wages (net of inflation) and a 3% discount rate. To do so, we first estimated the effective grades of schooling lost by adolescence (Totalgradesoflearninglost; see Equation 4) and then multiplied this figure by the expected wage increase per grade of education (return to education; RTE), the net present value of future wages (NPV(wages)), and the average days of instruction lost Closures, as shown in Equation 5: Similar to previous work (Fink et al., 2016), we assumed wages to correspond to two‐thirds of each country’s gross domestic product per capita (as reported by the World Bank, 2020). Given large variation in returns to schooling observed in the literature, as well as the difficulty associated with making appropriate real wage growth and interest rate projections for the future, we explored alternative assumptions in a set of sensitivity analyses. Specifically, we computed estimates under more modest and optimistic returns to education of 4, 8, and 10% per year of schooling, respectively, as well as with 0% and 3% net discounting of future benefits. In recent history, real interest rates have fluctuated between 0% and 5% (Borio et al., 2017), while real wage growth rates have been approximately 2% (Inclusive Labour Markets, 2015). The 0% scenario essentially assumes that real interest rates equal future real wage growth rates; the 3% net discounting scenario assumes that future interest rates will be 3% higher than real wage growth rates (i.e., wage growth rates net of inflation). Three percent net discounting would, for example, be appropriate with zero real (net of inflation) growth in wages, and a 3% discounting factor. It would also be appropriate for a more realistic real wage growth rate of 2% combined with a more conservative 5% discounting rate. Because we only had data available on actual ECCE closures through February 2, 2021, we also conducted a series of analyses to allow readers to forecast how ongoing disruptions to ECCE services may predict further losses. In particular, we estimated the implications of one additional month of ECCE shut‐downs on each of our outcomes. To do so, we used the same methods described above but replaced actual closure durations with a proportion of 0.083 (one‐twelfth of 1 year). For all analyses, we also present bootstrapped standard errors to account for statistical uncertainty in estimated (1) associations between ECCE attendance and probabilities of being developmentally off track using the MICS data, (2) associations between years participating in ECCE and adolescent PISA scores, (3) associations between schooling grade and PISA scores, and (4) economic returns to education. We employed 10,000 bootstrapped simulations and calculated the 2.5th and 97.5th percentiles of these draws to provide 95% confidence intervals around our estimated results.