UNITED NATIONS — Software magnate and philanthropist Bill Gates, who is helping spearhead a global campaign to eradicate polio, said Thursday he hopes that by 2015 no child in the world will be paralyzed by the disease and by 2018 polio will be wiped out.

Gates said in an interview with the Associated Press that the world is making “great progress” in the fight against polio and there are now only three countries where the polio virus has not been stopped — Pakistan, Afghanistan and Nigeria.

The Microsoft founder, who co-chairs the Bill and Melinda Gates Foundation, spoke ahead of a high-level meeting on the sidelines of the U.N. General Assembly which launched the new campaign to stamp out polio forever. Timothy Wirth, president of the United Nations Foundation, called it “the most important international meeting on polio eradication in the last 20 years.”

U.N. Secretary-General Ban Ki-moon said eradicating the virus is a priority during his second term, which began in January, and he has put “the strength of the entire United Nations system” behind the campaign.