A report by the Centers for Disease Control and Prevention in Atlanta says the number of infants worldwide who got the DTP vaccine at an all-time high and up 8 percentage points from 2000.
The cases of polio worldwide has been reduced by 99 percent and measles deaths have declined 78 percent, the report says.
"However, this global increase obscures large regional and local variations in access to health services; worldwide, more than 23 million children -- half of whom live in India and Nigeria -- did not receive three doses of DTP vaccine during the first year of life," health officials say in a statement.
"Introducing new vaccines such as pneumococcal vaccine and rotavirus vaccine has the potential to greatly reduce pneumonia and diarrhea, the two greatest causes of death among children age 5 and under in the developing world."
Increasing the number of children vaccinated has the potential to substantially reduce child morbidity and mortality worldwide, the report says.
The report was published Thursday in the CDC's Morbidity and Mortality Weekly Report.