Polio is an infectious disease, contracted predominantly by children, that can lead to the permanent paralysis of various body parts and can ultimately cause death by immobilizing the patient’s breathing muscles.

No cure exists for the symptoms, but in the 1950s effective vaccines were developed and have been used around the world since then. This allowed some richer countries to eliminate the disease entirely in the 1960s and 70s. But large outbreaks continued around the world and in the 1980s the estimated global number of total paralytic cases was over 350,000 per year and the disease was still prevalent in 125 countries. As a response the “Global Polio Eradication Initiative” (GPEI) was founded in 1988 to fight the virus’s spread and disease burden with a global vaccination campaign. Since then the world has made rapid progress against the disease and until 2016 the number of paralytic cases was reduced by 99.99% with 42 cases in that year worldwide.

As of 2017 the virus remains in circulation in only three countries in the world — Afghanistan, Pakistan and Nigeria — and it is hoped that the disease will soon be eradicated globally.

Read the full article about trying to eradicate polio permanently by Sophie Ochmann and Max Roser at Our World in Data.