LOL, the vaccine was introduced in the USA in 1955, in the Netherlands in 1957 (higher on the chart means more cases): https://ourworldindata.org/grapher/preva

LOL, the vaccine was introduced in the USA in 1955, in the Netherlands in 1957 (higher on the chart means more cases): https://ourworldindata.org/grapher/prevalence-of-polio-rates-in-the-united-states?country=~USA https://ourworldindata.org/grapher/prevalence-of-polio-rates... https://www.rivm.nl/polio https://www.rivm.nl/polio