**3. Vaccination and control strategies**

There is a wide variety of vaccine calendars in the world. By 2015, 86% of children worldwide (116.1 million) received three doses of diphtheria, tetanus, and pertussis (DTP) vaccines. However, to reach coverage of 95% or more, 13.5 million unvaccinated children should be vaccinated annually, and an additional 6 million children with incomplete vaccination should complete the timeline. Restricted access and missed opportunities for vaccination remain a challenge worldwide, as well as for middle- and upper-income countries [41].
