Global eradication efforts have "cornered” polio in a “few pockets” of Pakistan and Afghanistan, the last two countries where the virus continues to paralyze children.
Experts hailed the progress being made in tackling the “outbreak-prone” disease during a virtual briefing last week to mark a decade since India was declared polio-free in March 2014.
“We have Pakistan and Afghanistan [where polio is] still endemic, but the virus is cornered in very few pockets in very few districts of these two countries,” said Dr. Ananda Bandyopadhyay, deputy director of polio technology, research and analytics at the Bill & Melinda Gates Foundation.
“The virus is gasping in these last corridors,” Bandyopadhyay said.
Pakistan has reported two wild poliovirus cases this year, while the number stood at six in 2023. Afghanistan has yet to detect a polio case this year and recorded six cases last year.
Experts credited continued efforts to vaccinate populations with pushing polio to the verge of extinction.
Wild poliovirus affects young children and can paralyze them in severe cases or can be deadly in certain instances. The paralytic disease is the only currently designated public health emergency of international concern.
Hamid Jafari, director of polio eradication for the WHO Eastern Mediterranean Region, told the event that until 2020, about 13 families of wild poliovirus had spread across the neighboring countries.
Since then, only two families have survived, and they remain endemic to Pakistan “in a very small geographic area” in southern parts of the Khyber Pakhtunkhwa border province and in eastern Afghanistan, he said.
While the “historic reservoirs” have been cleared of the virus in Pakistan and Afghanistan, transmission is now surviving in “exceptionally hard-to-reach” populations, making it difficult for polio teams to inoculate children there, he said.
Jafari said "militancy and extensive population movement" across the Afghanistan-Pakistan border, and keeping track of those populations, were the kinds of "last-mile challenges that we have.”
“The genetic cluster that seems to be on its way out and getting eliminated is in the heart of the area of militancy in Pakistan,” he said.
Jafari noted that India’s polio program did not face the same militancy challenge that Afghanistan's did until the Taliban takeover in August 2021, and that it remains a significant problem in Pakistan in the last stages of eradicating the virus.
Bandyopadhyay said successes against the poliovirus in both countries raise hope it is on the verge of extinction there.
He said clinicians “observed similar trends” even in the countries that “saw polio’s disappearing act.”
“Initially, we would have multiple families or lineages of the virus … and then you saw that disappearing act,” he said.
Jafari said that lessons learned in India had been applied to Nigeria, which was declared polio-free in June 2020. He added that many of “these practices were instilled in the program” in Pakistan and Afghanistan.
WHO has said that cases caused by wild poliovirus have dropped by more than 99% since 1988, from an estimated 350,000 in more than 125 endemic countries to just two endemic countries as of October 2023.
It attributed the decline to the Global Polio Eradication Initiative, led by the WHO, the U.N. Children’s Fund, Rotary International, the U.S. Centers for Disease Control and Prevention, and the Bill & Melinda Gates Foundation.
Jay Wenger, director of the polio program at the Gates Foundation, said that even though Afghanistan and Pakistan had reported a handful of cases, global efforts against the virus must continue.
“As we get to the end of the [polio program], it’s critical to finish. We usually say if there is polio anywhere, it's a threat to everywhere,” he said.
