We are on the cusp of a historic moment for global public health. The potential exists for wild polio to be wiped out this year, becoming only the second human disease ever eradicated. Eradication of a disease is the ultimate goal of public health as it ensures everyone is permanently protected against the disease.
Just 30 years ago, there were 350,000 cases of polio each year, and the disease was endemic in 125 countries. In 2017, we had just 22 cases (> 99.99% reduction) in two countries. Today, we face challenges in finishing the job. We need to succeed because failure to eradicate polio from the remaining strongholds could result in a resurgence of the disease with as many as 200,000 new cases every year within a decade.
The last mile of disease eradication is always a challenge. For polio, it has uncovered a number of unexpected issues. For instance, it was found that the oral polio vaccine, which uses a genetically weakened version of the live virus, could trigger the disease in people similar to the wild virus. Last year, we worked with the Global Polio Eradication Initiative (GPEI) to successfully replace the original oral vaccine with a safer version in 155 countries. This unprecedented accomplishment was achieved globally in one month as a result of intense planning and partner coordination. This feat also demonstrated the world’s commitment to eradicating polio.
Another unexpected finding during the eradication effort has been that some immune-deficient people unknowingly excrete virus – sometimes for years. These individuals are at risk of becoming paralyzed themselves and potentially causing an outbreak in under-immunized populations post wild virus eradication. As the secretariat for the Polio Antivirals Initiative, The Task Force for Global Health has been working with the pharmaceutical company ViroDefense Inc. to develop two drugs that can be used to potentially stop virus replication in immune-deficient people who excrete poliovirus. The availability of two therapies would provide an essential tool to help assure a polio free world.
The Task Force is also playing a role in another key aspect of preventing outbreaks post-eradication. We serve as the secretariat for the US National Certification Committee that is in place to ensure that samples of poliovirus in laboratories in the United States are destroyed or are kept in secure facilities. In the United States, we support efforts to safely contain these samples so that they cannot be introduced into the population.
Significant resources have been devoted to eradicating polio around the world over the past 30 years. In fact, the immunization programs of some countries are almost entirely dependent on polio funding. Although there will be much to celebrate when wild poliovirus is eradicated, we must ensure that the health infrastructure built with polio funds is not lost. We are working with our partners to help countries develop plans to remain polio free while they transition to other sources of funding to support their health priorities.
While obstacles remain, we are optimistic we can stop transmission of wild poliovirus in 2018. Polio surveillance and vaccination with the live oral vaccine will continue in most parts of the world for three years until eradication is certified. After certification, only the inactivated vaccine form will only be used. If we stop wild poliovirus transmission this year and there are no other cases detected in the next three years, we will then be able to celebrate a hard earned and equitable polio-free world.
Mark McKinlay, PhD, is director for the Center for Vaccine Equity (CVE), a program of The Task Force for Global Health. In this role, he oversees The Task Force’s polio eradication and pandemic preparedness programs.