The World Health Organization has declared this week World Immunization Week. The agency is some five years into a global plan to save millions of lives by sparing them from preventable diseases in the developing world.

Efforts are underway to try the first malaria vaccine in Ghana, Kenya and Malawi, and the push to eradicate viral hepatitis includes major vaccinations at time of birth. A new injection for preventing rotavirus and deadly diarrhea in places like the poorest regions of Africa was demonstrated in a study last month, offering promise of saving hundreds of thousands of human lives annually.

But nearly 20 million children remain unvaccinated or under-vaccinated across the world – including a growing number in the United States and other first world nations, where “anti-vaxxer” choice has opened up new epidemics of measles and other diseases that were nearing eradication.

So while vaccination has proven to eradicate small pox and push polio to the brink, the reluctance to immunize may be one of the greatest advantages in the diseases’ arsenal.

The Global Vaccine Action Plan was unveiled in May 2012, and was endorsed by 194 countries. It laid out an ambitious plan to prevent millions of deaths through the year 2020.

But the WHO said today in its announcement of the World Immunization Week that all of the target milestones for elimination target diseases are behind schedule. The list includes measles, rubella, and maternal and neonatal tetanus. In fact, global immunization coverage has increased by only 1 percent since 2010, the agency said.

“In order for everyone, everywhere to survive and thrive, countries must make more concerted efforts to reach GVAP goals by 2020,” the WHO said today in a statement. “Additionally, those countries that have achieved or made forward progress towards achieving the goals must work to sustain those efforts over time.”

Overall progress has been made. Only 73 percent of the world’s infants had received a dose of measles vaccine in the year 2000. But in 2015, that rate had climbed to 85 percent for the all world’s children by the age of 1 year.

But at the beginning of 2017, measles continues to spread in certain pockets of the United States. As of March 25, 28 people from 10 states had contracted measles, according to the Centers for Disease Control and Prevention. It’s the latest in a series of rolling outbreaks. The biggest being 667 cases spread among some 23 outbreaks. Almost all cases are driven by unvaccinated people, who can spread the germs to even those who are vaccinated. Another recent outbreak was linked to as California amusement park in 2015.

The outbreaks follow the 2000 documentation of “measles elimination” in 2000.

The rate of vaccination among kindergarteners across the U.S. remains at roughly 94 percent for key immunizations, according to the latest CDC counts published in October 2016. Those key vaccines are two doses of the measles, mumps and rubella vaccine; the diphtheria, tetanus and acellular pertussis vaccine; and the two-dose varicella vaccine.

But those rates are uneven. For while Maryland and Mississippi have vaccination rates over 99 percent, some others have rates below 90 percent: 87.1 percent in Colorado and 88.5 percent in Washington, D.C., according to the CDC counts.