An estimated 169 million children globally did not receive the first dose of the measles vaccine between 2010 and 2017, with UNICEF warning "widening pockets of unvaccinated children have created a pathway to the measles outbreaks hitting several countries around the world today".
The warning comes as latest figures show more than 110,000 measles cases were reported worldwide in the first three months of 2019, up nearly 300 per cent from the same period last year.
Globally, coverage of the first dose of the measles vaccine was reported at 85 per cent in 2017, while coverage for the second dose is 67 per cent.
In high-income countries, while coverage with the first dose is 94 per cent, coverage for the second dose drops to 91 per cent.
The United States tops the list of high-income countries with the most children not receiving the first dose of the vaccine between 2010 and 2017 (2,593,000), followed by France (608,000) and the United Kingdom (527,000).
Worldwide coverage levels of the second dose of the measles vaccines are even lower, with data showing of the top 20 countries with the largest number of unvaccinated children in 2017, nine have not introduced the second dose.