The data highlight inequality in child deaths among 194 surveyed countries. Of the 5.9 million deaths last year, 3.6 million happened in India, Nigeria, Pakistan, the Democratic Republic of Congo, Ethiopia, China, Angola, Indonesia, Bangladesh and Tanzania.
The two leading causes were complications due to premature birth and pneumonia, said researchers from the Johns Hopkins Bloomberg School of Public Health, the London School of Hygiene and Tropical Medicine and the World Health Organisation.
They said child survival has improved substantially, although countries failed to meet the UN Millennium Development Goals (MDGs) to cut the rate of under-five deaths by two-thirds between 1990 and 2015. The rate fell by 53 percent over the period.
The study's lead author Li Liu from the Johns Hopkins Bloomberg School of Public Health underlined uneven progress in the MDGs implementation, adding that substantial progress is needed for countries in sub-Saharan Africa and Southern Asia to achieve the child survival target.
The researchers recommended breastfeeding, vaccines for pneumonia, malaria and diarrhea, as well as improving water and sanitation to help with children's survival.