Trickle-down innovation and the longevity of nations

The diffusion of innovations such as antibiotics, water purification, waste removal, milk pasteurisation, hand-washing campaigns, sterilisation of surgical instruments, oral rehydration therapy, and vaccination campaigns, are likely to have contributed to improving life expectancies for low-income countries.3 Large increases in per-capita income might not be necessary or sufficient for such innovations to materialise in a country; other factors, such as the willingness to adopt new practices and technologies, and the ability to create and maintain institutions that can deliver them, are also important. [...]as a country's population ages and becomes more affluent, so too does the pressure to invest in medical innovations focusing on age-related diseases (which are often available to, and for, a narrow subset of the population) over public health and social services that benefit the general public. [...]the populations of low-income countries are not homogenous, and the diseases that afflict high-income individuals within poor countries differ, sometimes substantially, from those afflicting lower-income groups.