Julie Potyraj, Community Manger of the online Master of Health Administration at The Milken Institute School of Public Health, George Washington University.

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A measles rubella vaccine ready for use. Photo: Gavi/ Christine McNab.

Whether in Uganda or the USA, vaccinating against infectious disease has become an important part of modern day health care, effectively preventing unnecessary morbidity and mortality. But since it is also measured in all countries across the world, immunization coverage can also tell us a great deal about a nation’s health system.

This is particularly the case for measles vaccination coverage, since it requires very high percentage of people to be immunized to prevent outbreaks. Vaccination coverage must be at least 95% for herd immunity – the point at which community vaccination levels will prevent a disease from spreading – to be effective. When coverage does not reach this number, sustained community transmitted outbreaks can start to occur. This can make measles the “canary in the coal mine” when it comes to gauging how well other vaccines are reaching populations and can give us clues about a health system.

But as we all know, measles outbreaks can and do happen across the world wherever, for different reasons, children are missing out on their measles shots. To put this in perspective, the Milken Institute School of Public Health at the George Washington University recently used this measure to take a snapshot of healthcare systems in the USA and a variety of other countries.

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Countries measured: India, Afghanistan, France, Ghana, US, Colombia, Australia, Algeria, Canada, Japan, Singapore, UK, Germany, Mongolia, Russia, China. Find the full infographic here.

Measles was considered eliminated from the United States in the year 2000, but thanks to low coverage and the lack of herd immunity, this is no longer the case. A great example of this was in 2014–2015 in what is now infamously known as the Disneyland outbreak. Although the original source has not been identified, the strain was linked to one that had been circulating throughout the Philippines the year before. By February 2015, 125 people in the United States (mostly California) had been infected with measles due to primary or secondary exposure originating at the Disney theme parks. Of the patients with known vaccination statuses, 79% had not received any measles immunization dosages, and 19% had received an incomplete dosage. Twelve, or 24% of the 79% who had not received any doses of the vaccine, were too young to be vaccinated and the rest were intentionally unvaccinated.

On the other side of the globe, the World Health Organization declared that Mongolia was measles free in July 2014. In 2013, Mongolia succeeded in having one of the highest immunization rates for measles in the world at 97%.  However, from March through August 2015, there had been more than 16,000 confirmed cases of the disease. Many of those affected were infants too young to be vaccinated; however, adults and older children were infected as well. In response, the Mongolian government started campaigns to revaccinate adults.

We know that vaccination is an effective way to prevent infectious disease outbreaks. As the Disneyland and Mongolia examples show, measles can strike anywhere; before it does, we must all remember the importance of high measles vaccination coverage, even after the disease has been officially eliminated. Until measles is eradicated globally, this is the only way to stay protected.