https://blogs.scientificamerican.com/observations/winning-the-infectious-disease-marathon/

More children are immunized today than ever before, and the number of new vaccines that children in poor countries have access to is also at its highest. This means that globally children have never been better protected against infectious disease in history. But while this is true in terms of absolute numbers, the latest data reveal some worrying new trends when you look at the proportion of children protected.

The first trend confirms our fears that the global percentage of children receiving routine immunization—as measured by three doses of a diphtheria-tetanus-pertussis vaccine, or DTP3—has stagnated, levelling off at 85 percent. The second, perhaps even more alarming, is that despite falling from 28 million in 2000 to around 16 million today, the number of children in the world’s 68 poorest countries that are missing out on DTP3 has now started to rise.