NEW DELHI, Nov. 2 -- The world's progress in improving health and development-related outcomes for people everywhere is one of the greatest success stories of the past 20 years. Two decades ago, the infectious diseases that killed or harmed millions often went unchecked. Children born in poor countries were only vaccinated against a handful of the same diseases as children born in wealthier countries. There was no access to life-saving drugs such as antiretrovirals to treat HIV. But if we look closely at the trajectory of healthcare, we realise that since the 1990s, we have nearly halved the number of women who die in childbirth and halved the number of children who die before the age of five.

There are many reasons for these gains. As cou...