In most regions, over the past 50 years, socioeconomic development has been accompanied by large falls in fertility and equally dramatic increases in life expectancy. 1 This phenomenon has led to rapidly ageing populations around the world. The fastest change is occurring in low- and-middle-income countries. Even in sub-Saharan Africa, which has the world’s youngest population structure, the number of people older than 60 years is expected to increase by over threefold, from 46 million in 2015 to 147 million in 2050. 2
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