July 16 (UPI) -- Nearly 20 million children worldwide were not properly vaccinated last year, leading to greater concern about potential outbreaks of preventable illnesses, a new U.N. report said.
The annual report Monday from the WHO and United Nations Children's Fund showed 19.4 million children weren't fully vaccinated in 2018 -- an increase over 19 million in 2017 and 18.5 million the year before.
WHO researchers said war, inequality and complacency are the primary contributors as to why children go without vaccines. Nearly half live in just 16 countries, including some of the most war-torn -- Afghanistan, Iraq, Pakistan, Yemen and Somalia.
"It's often those who are most at risk -- the poorest, the most marginalized, those touched by conflict or forced from their homes -- who are persistently missed," WHO Director-General Tedros Adhanom Ghebreyesus said in a statement. "Far too many are left behind."
Those children, the report says, are less likely to have access to proper medical care.
UNICEF Executive Director Henrietta Fore said measles, for example, is a real-time gauge of where improvements can be made. Measles cases more than doubled last year, with 350,000 reported worldwide.
"Because measles is so contagious, an outbreak points to communities that are missing out on vaccines due to access, costs or, in some places, complacency," Fore said. "We have to exhaust every effort immunize every child."
Measles cases in the United States have dramatically increased so far this year to a level not seen in nearly 30 years. The number of cases -- more than 1,000 in at least 28 states -- are the most on record since 1992.