Reaching more children with vaccines in developing countries: key challenges of innovation and delivery

As we reach the deadline for the United Nations fourth Millennium Development Goal to reduce child mortality, many inequalities in vaccine access still exist, particularly for children in developing countries. Here we discuss some of the barriers to vaccine access in these countries, as well as some of the innovative approaches that could address these. Finally, we discuss the need to create a global environment conducive to innovation directed at low-resource settings, aimed to ultimately increase vaccine coverage.