This weekend marks the start of a global effort that health officials are hoping will be the final push to eradicate polio.
The process involves 150 countries that have to switch vaccines, which is complicated and expensive.
Doctor Steve Cohi from the Centers for Disease Control and Prevention joined NewsHour’s Alison Stewart to discuss.
“We’re on the verge of completely finishing the job of eradicating polio,” he said.
The countries are expected to switch from the trivalent vaccine, first developed in 1961, to the bivalent one, which contains only the type 1 and 3 polio viruses, over the next two weeks.
The campaign is led by the World Health Organization along with the CDC, UNICEF, the Bill and Melinda Gates Foundation and Rotary International.
Attempts for polio eradication began in 1988, when there were 355,000 cases per year in 125 countries. The disease has since been reduced by more than 99 percent and new cases are only found in two countries, Pakistan and Afghanistan.
If this final push is successful, it will be the second disease to be eradicated since smallpox was quashed in 1980, according to Reuters.