Over the last 50 years we have witnessed the full expression of the power of vaccines. A concerted global effort to interrupt disease transmission began in 1966 with the Smallpox Eradication Programme, before transitioning during the 1970s to an Expanded Programme on Immunization (EPI) in order to vaccinate a generation of infants against diphtheria, pertussis, tetanus, measles, polio, and tuberculosis. With the 2000 launch of the Millennium Development Goals, the Bill & Melinda Gates Foundation pledged $750 million to create Gavi, The Vaccine Alliance, which expanded coverage of the EPI vaccines, while simultaneously introducing several new vaccines, including those targeting rotavirus and pneumococcal disease.

We’ve now begun to evaluate the successes of these initiatives. According to the Global Burden of Disease Study (GBD), between 1990 and 2010, there has been up to an 80 percent reduction in deaths from vaccine preventable diseases. A dramatic example is the benefit of global measles vaccination. Prior to EPI measles was one of the world’s leading global killers of children, accounting for millions of deaths annually. By 1990, according to the GBD, 631,200 people died of measles and its complications. Currently, less than 100,000 die annually.

But these gains can be fragile. Measles is so highly transmissible that any let down in vaccine coverage can result in outbreaks. In JAMA last year Daniel Salmon at the Johns Hopkins Institute of Vaccine Safety and Saad Omer at Emory’s Rollins School of Public Health reported that most of the recent US measles outbreaks occurred due to “intentionally unvaccinated” individuals.

Recently I expressed concerns that an American neo-antivaccine movement is underway, and we should expect measles outbreaks to resume and increase in their frequency or severity. Its beginnings are in Texas where a well-run political action committee has formed and at least 45,000 schoolchildren have been exempted from receiving their vaccines for non-medical reasons. Nationally, “Vaxxed,” a faux documentary alleging a vast conspiracy and cover-up at the CDC, has been showing across the country, while in a few weeks anti-vaccine groups will stage a march on Washington DC. We have heard that a new national commission may form that (depending on its composition) could potentially re-open the wounds first created in the US Congress by house member Dan Burton.

I’m the parent of an adult daughter with autism, as well as the head of a university-based non-profit institute that develops vaccines for poverty-related neglected diseases. I’m worried that America’s anti-vaccine movement has sufficient strength and momentum to affect vaccine coverage globally. Whether it’s Hollywood movies, rap music, or soft drinks, the world is quick to embrace American culture. The “Vaxxed” tour has already begun with showings so far in the United Kingdom, Australia, and elsewhere, but I’m especially concerned about the large middle- and low-middle income nations such as Bangladesh, Brazil, China, India, Indonesia, Nigeria, and Russia. A small drop in measles vaccine coverage in those nations would lead to measles outbreaks and deaths on a scale that we haven’t seen since the years prior to EPI. In so doing we could see a reversal of the gains achieved since 2000 through the Global Goals: The Millennium Development Goals and the new Sustainable Development Goals.

Groups have set up to track the global spread of ‘vaccine hesitancy’, and have made some interesting (and often non-intuitive) findings. Last year Heidi Larson and her colleagues based in London found that among 67 countries, France, Bosnia & Herzegovina, Russia, and Ukraine rank among nations with the highest percentage of people who question the safety of vaccines. They also found that high educational attainment and socioeconomic status is linked to vaccine hesitancy, suggesting to me that the negative (and erroneous) buzz about vaccines and autism is likely a factor.

Things might only get worse pending the imminent expansion and export of an American-led antivaccine movement. We need to recognize that the current activities in Texas and Washington DC could ignite reversals of global disease elimination and eradication efforts that are now more than 50 years in the making. Given these high stakes, I believe the leaders in the US Government must become more vocal and proactive, while addressing and elevating discussions about vaccine hesitancy and antivaccine movements in international forums. Because there are particular consequences of reduced vaccine coverage in some of the largest nations comprising the group of 20 (G20), future G20 summits might be an appropriate venue for coordinated action, in addition to the upcoming World Health Assembly in May. An American antivaccine movement is building and we need to take steps now to snuff it out.