developing countries, especially least developed countries and small island developing States." This target has one indicator: Indicator 4.c.1 is "Proportion of teachers in) pre-primary; (b) primary; (c) lower secondary; and (d) upper secondary education who have received at least the minimum organized teacher training (e.g. pedagogical training) pre-service or in-service required for teaching at the relevant level in a given country" Sub-Saharan Africa is behind with the lowest percentages of trained teachers in pre-primary (48 percent), primary (64 percent), and secondary (50 percent) education in 2017. A report from 2020 found that the percentage of primary school teachers receiving the minimum pedagogical training according to national standards has stagnated at 85 percent since 2015. The percentage is lowest in sub-Saharan Africa (64 percent) and Southern Asia (72 percent). Custodian agencies The custodian agency for most of the indicators of the targets is UNESCO-UIS. In addition, UNESCO is the custodian agency for some of the indicators. The International Telecommunication Union is the custodian agency for Indicator 4.4.1. OECD is the custodian agency for Indicator 4.b.1. UNESCO-ED/PSD/ESD is the custodian agency for indicator 4.7.1. Challenges Impact of COVID-19 pandemic Just as all SDGs, achieving SDG 4—for inclusive and equitable access to education—is likely to be missed due to the COVID-19 pandemic. There is a projection that more than 200 million children will still be out of education by 2030. COVID-19 highlighted the significance of health literacy and the system's failure to provide an equal opportunity of education for everyone. Health literacy can be described as the ability of an individual to make decisions based on healthcare provider’s advice. Actions are called to include health literacy in basic educational curriculum systems to foster educated individuals to slow down the spread of diseases such as COVID-19. After the pandemic hit, school closure (including universities) starting in April 2020 affected up to 91 percent of enrolled learners. Most of the world's children were deprived of formal education during the COVID-19 outbreak—a legacy that could threaten the SDGs' underlying ambition to leave no one behind (LNOB). Many educational institutions are attempting to maintain programs through online education. In OECD countries, although the impact of COVID-19 was huge, there are also possibilities to generate new types of education system. However, equity remains a major constraint on access to distance learning, as many students in developing countries do not either have access to the internet or a safe