Africa declared free of wild polio in 'milestone' - BBC News
History of polio - BBC News
History of Polio – GPEI
History of Polio – GPEI
Polio - Wikipedia
Risk factors for the spread of vaccine-derived type 2 polioviruses after global withdrawal of trivalent oral poliovirus vaccine and the effects of outbreak responses with monovalent vaccine: a retrospective analysis of surveillance
Polio detected in NYC's sewage, suggesting virus circulating | AP News
What is Polio?
Polio - Our World in Data
What to know about the polio vaccine and why most people aren't at risk of infection - ABC News
What You Need to Know About Polio and How to Protect Yourself
Wiping Out Polio: How The U.S. Snuffed Out A Killer : Shots - Health News : NPR