Before the development of the first poliovirus vaccine in 1955, poliomyelitis paralysed and killed up to half a million people every year.

By 2000, mass vaccination campaigns, armed with new types of oral polio vaccines, had almost eradicated wild poliovirus, except for a few isolated regions.

In 2020, the whole African region was declared free of wild poliovirus, leaving just two countries yet to stop the spread of the disease: Afghanistan and Pakistan.

Mass immunization programs had Pakistan on the brink of eradicating polio in 2023, with just six remaining cases of the wild form of the virus. But now, cases are climbing again — 73 cases were reported in 2024.

"It has spread to all districts of Pakistan. We've snatched defeat from the jaws of victory," said Zulfiqar Bhutta, Hospital for Sick Children, Toronto, Canada.

The reason, Bhutta writes in a commentary in the Lancet, is that cases of poliovirus are spilling over the border from Afghanistan. The genetic strains of wild poliovirus in Pakistan are all from Afghanistan.

Bhutta leads groups working on child immunization strategies in conflict zones. He was involved in the largest trials of poliovirus vaccine interventions in........

© Deutsche Welle